Most modern operating systems use a 'hosts' file, or some varient. What this 'hosts' file does is explained in /etc/hosts.
Using the hosts file on your system to redirect the hostname of banner ad servers to 127.0.0.1 (your computer), you can prevent many banner ads for ever getting a chance of loading. Put simply, you can use this to block a lot of ads from websites without extra software and minimal effort.
Step 1:
Open up your system's hosts file. Depending on your operating system, it may
be any of the following.
Windows NT/2000 - c:\winnt\system32\drivers\etc\hosts
Windows XP - c:\windows\system32\drivers\etc\hosts
Linux/BSD/Solaris/*n?x - /etc/hosts
BeOS - /boot/beos/etc/hosts
(Some of these systems may not allow you to view or edit the hosts file
unless you are root/administrator)
The file will probably be little more then 127.0.0.1 localhost.
Step 2:
With that file open on your system, paste the following into it below the 127.0.0.1 localhost bit.
127.0.0.1 207-87-18-203.wsmg.digex.net
127.0.0.1 Garden.ngadcenter.net
127.0.0.1 Ogilvy.ngadcenter.net
127.0.0.1 ResponseMedia-ad.flycast.com
127.0.0.1 Suissa-ad.flycast.com
127.0.0.1 UGO.eu-adcenter.net
127.0.0.1 VNU.eu-adcenter.net
127.0.0.1 a32.g.a.yimg.com
127.0.0.1 ad-adex3.flycast.com
127.0.0.1 ad.abcnews.com
127.0.0.1 ad.adsmart.net
127.0.0.1 ad.au.doubleclick.net
127.0.0.1 ad.ca.doubleclick.net
127.0.0.1 ad.de.doubleclick.net
127.0.0.1 ad.doubleclick.net
127.0.0.1 ad.fr.doubleclick.net
127.0.0.1 ad.icq.com
127.0.0.1 ad.jp.doubleclick.net
127.0.0.1 ad.keenspace.com
127.0.0.1 ad.linkexchange.com
127.0.0.1 ad.linksynergy.com
127.0.0.1 ad.nl.doubleclick.net
127.0.0.1 ad.no.doubleclick.net
127.0.0.1 ad.preferences.com
127.0.0.1 ad.sma.punto.net
127.0.0.1 ad.trafficmp.com
127.0.0.1 ad.uk.doubleclick.net
127.0.0.1 ad.webprovider.com
127.0.0.1 ad08.focalink.com
127.0.0.1 adcontroller.unicast.com
127.0.0.1 adcreatives.imaginemedia.com
127.0.0.1 adex3.flycast.com
127.0.0.1 adforce.ads.imgis.com
127.0.0.1 adforce.imgis.com
127.0.0.1 adfu.blockstackers.com
127.0.0.1 adimage.blm.net
127.0.0.1 adimages.earthweb.com
127.0.0.1 adimg.egroups.com
127.0.0.1 admedia.xoom.com
127.0.0.1 adpick.switchboard.com
127.0.0.1 adremote.pathfinder.com
127.0.0.1 ads.ad-flow.com
127.0.0.1 ads.admaximize.com
127.0.0.1 ads.admonitor.net
127.0.0.1 ads.bfast.com
127.0.0.1 ads.clickagents.com
127.0.0.1 ads.clickhouse.com
127.0.0.1 ads.enliven.com
127.0.0.1 ads.fairfax.com.au
127.0.0.1 ads.fool.com
127.0.0.1 ads.freshmeat.net
127.0.0.1 ads.hollywood.com
127.0.0.1 ads.i33.com
127.0.0.1 ads.icq.com
127.0.0.1 ads.infi.net
127.0.0.1 ads.jwtt3.com
127.0.0.1 ads.link4ads.com
127.0.0.1 ads.lycos.com
127.0.0.1 ads.madison.com
127.0.0.1 ads.mcafee.com
127.0.0.1 ads.mediaodyssey.com
127.0.0.1 ads.msn.com
127.0.0.1 ads.musiccity.com
127.0.0.1 ads.newcity.com
127.0.0.1 ads.ninemsn.com.au
127.0.0.1 ads.seattletimes.com
127.0.0.1 ads.smartclicks.com
127.0.0.1 ads.smartclicks.net
127.0.0.1 ads.snowball.com
127.0.0.1 ads.sptimes.com
127.0.0.1 ads.tripod.com
127.0.0.1 ads.web.aol.com
127.0.0.1 ads.webcoretech.com
127.0.0.1 ads.x10.com
127.0.0.1 ads.xtra.co.nz
127.0.0.1 ads.zdnet.com
127.0.0.1 ads01.focalink.com
127.0.0.1 ads02.focalink.com
127.0.0.1 ads03.focalink.com
127.0.0.1 ads04.focalink.com
127.0.0.1 ads05.focalink.com
127.0.0.1 ads06.focalink.com
127.0.0.1 ads08.focalink.com
127.0.0.1 ads09.focalink.com
127.0.0.1 ads1.activeagent.at
127.0.0.1 ads10.focalink.com
127.0.0.1 ads11.focalink.com
127.0.0.1 ads12.focalink.com
127.0.0.1 ads14.focalink.com
127.0.0.1 ads16.focalink.com
127.0.0.1 ads17.focalink.com
127.0.0.1 ads18.focalink.com
127.0.0.1 ads19.focalink.com
127.0.0.1 ads2.zdnet.com
127.0.0.1 ads20.focalink.com
127.0.0.1 ads21.focalink.com
127.0.0.1 ads22.focalink.com
127.0.0.1 ads23.focalink.com
127.0.0.1 ads24.focalink.com
127.0.0.1 ads25.focalink.com
127.0.0.1 ads3.zdnet.com
127.0.0.1 ads3.zdnet.com
127.0.0.1 ads4.realcities.com
127.0.0.1 ads5.gamecity.net
127.0.0.1 adserv.iafrica.com
127.0.0.1 adserv.quality-channel.de
127.0.0.1 adserver.dbusiness.com
127.0.0.1 adserver.garden.com
127.0.0.1 adserver.janes.com
127.0.0.1 adserver.matchcraft.com
127.0.0.1 adserver.merc.com
127.0.0.1 adserver.monster.com
127.0.0.1 adserver.portalofevil.com
127.0.0.1 adserver.track-star.com
127.0.0.1 adserver1.backbeatmedia.com
127.0.0.1 adserver1.ogilvy-interactive.de
127.0.0.1 adtegrity.spinbox.net
127.0.0.1 antfarm-ad.flycast.com
127.0.0.1 au-ads.admonitor.net
127.0.0.1 au.ads.link4ads.com
127.0.0.1 banner.media-system.de
127.0.0.1 banner.orb.net
127.0.0.1 banner.relcom.ru
127.0.0.1 banners.easydns.com
127.0.0.1 banners.looksmart.com
127.0.0.1 banners.stilenet.com
127.0.0.1 banners.wunderground.com
127.0.0.1 barnesandnoble.bfast.com
127.0.0.1 beseenad.looksmart.com
127.0.0.1 bizad.nikkeibp.co.jp
127.0.0.1 bn.bfast.com
127.0.0.1 c3.xxxcounter.com
127.0.0.1 califia.imaginemedia.com
127.0.0.1 cds.mediaplex.com
127.0.0.1 click.avenuea.com
127.0.0.1 click.go2net.com
127.0.0.1 click.linksynergy.com
127.0.0.1 cookies.cmpnet.com
127.0.0.1 cornflakes.pathfinder.com
127.0.0.1 counter.hitbox.com
127.0.0.1 crux.songline.com
127.0.0.1 erie.smartage.com
127.0.0.1 etad.telegraph.co.uk
127.0.0.1 fmads.osdn.com
127.0.0.1 fp.valueclick.com
127.0.0.1 gadgeteer.pdamart.com
127.0.0.1 gamma.adroar.com
127.0.0.1 global.msads.net
127.0.0.1 gm.preferences.com
127.0.0.1 gp.dejanews.com
127.0.0.1 hg1.hitbox.com
127.0.0.1 image.click2net.com
127.0.0.1 image.eimg.com
127.0.0.1 images.ads.fairfax.com.au
127.0.0.1 images2.nytimes.com
127.0.0.1 img-iad.wip.mediaplex.com
127.0.0.1 jobkeys.ngadcenter.net
127.0.0.1 kansas.valueclick.com
127.0.0.1 leader.linkexchange.com
127.0.0.1 liquidad.narrowcastmedia.com
127.0.0.1 ln.doubleclick.net
127.0.0.1 m.doubleclick.net
127.0.0.1 m.tribalfusion.com
127.0.0.1 macaddictads.snv.futurenet.com
127.0.0.1 maximumpcads.imaginemedia.com
127.0.0.1 media.preferences.com
127.0.0.1 mercury.rmuk.co.uk
127.0.0.1 mojofarm.sjc.mediaplex.com
127.0.0.1 nbc.adbureau.net
127.0.0.1 newads.cmpnet.com
127.0.0.1 ng3.ads.warnerbros.com
127.0.0.1 ngads.smartage.com
127.0.0.1 nsads.hotwired.com
127.0.0.1 ntbanner.digitalriver.com
127.0.0.1 ph-ad05.focalink.com
127.0.0.1 ph-ad07.focalink.com
127.0.0.1 ph-ad16.focalink.com
127.0.0.1 ph-ad17.focalink.com
127.0.0.1 ph-ad18.focalink.com
127.0.0.1 rd.advertising.com
127.0.0.1 rd.yahoo.com
127.0.0.1 realads.realmedia.com
127.0.0.1 redherring.ngadcenter.net
127.0.0.1 redirect.click2net.com
127.0.0.1 regio.adlink.de
127.0.0.1 retaildirect.realmedia.com
127.0.0.1 s2.focalink.com
127.0.0.1 servedby.advertising.com
127.0.0.1 sh4sure-images.adbureau.net
127.0.0.1 spin.spinbox.net
127.0.0.1 st.clickagents.com
127.0.0.1 st.valueclick.com
127.0.0.1 static.admaximize.com
127.0.0.1 stats.superstats.com
127.0.0.1 sview.avenuea.com
127.0.0.1 thinknyc.eu-adcenter.net
127.0.0.1 tracker.clicktrade.com
127.0.0.1 tribalfusion.speedera.net
127.0.0.1 tsms-ad.tsms.com
127.0.0.1 us.a1.yimg.com
127.0.0.1 us.i1.yimg.com
127.0.0.1 v0.extreme-dm.com
127.0.0.1 v1.extreme-dm.com
127.0.0.1 van.ads.link4ads.com
127.0.0.1 view.accendo.com
127.0.0.1 view.avenuea.com
127.0.0.1 w113.hitbox.com
127.0.0.1 w25.hitbox.com
127.0.0.1 web2.deja.com
127.0.0.1 webads.bizservers.com
127.0.0.1 www.PostMasterBannerNet.com
127.0.0.1 www.ad-up.com
127.0.0.1 www.admex.com
127.0.0.1 www.alladvantage.com
127.0.0.1 www.burstnet.com
127.0.0.1 www.commission-junction.com
127.0.0.1 www.eads.com
127.0.0.1 www.freestats.com
127.0.0.1 www.imaginemedia.com
127.0.0.1 www.netdirect.nl
127.0.0.1 www.oneandonlynetwork.com
127.0.0.1 www.targetshop.com
127.0.0.1 www.teknosurf2.com
127.0.0.1 www.teknosurf3.com
127.0.0.1 www.valueclick.com
127.0.0.1 www.websitefinancing.com
127.0.0.1 www2.burstnet.com
127.0.0.1 www4.trix.net
127.0.0.1 www80.valueclick.com
127.0.0.1 z.extreme-dm.com
127.0.0.1 z0.extreme-dm.com
127.0.0.1 z1.extreme-dm.com
Save the changes.
Now ads from any of those servers will be unable to load. (Some systems may require a reboot for changes to come into effect)
Step 3:
There is no step 3.
The list will always be incomplete; if you find an adserver hostname that is not on the list above, don't create a new writeup below, please /msg a God or Content Editor and ask them to add it.
Also, standard disclaimer: This is all at your own risk... blah blah etc. If using this makes your computer explode, don't blame me.
Have fun!
VirtualWolf: I didn't specify Mac OS because I couldn't test it myself. As far as I knew Classic Mac OS uses a different style of hosts file, and I just thought Mac OS X would be covered by the *n?x bit. It's not, though...