If you ever arrive in Antwerp as a tourist try to get your hands on a 'week-up'. It's a small magazine that is distributed for free in the bars and pubs and it contains the sacred and mystical knowledge of 'Parties and Events in Antwerp'. There's also a version available on-line (www.weekup.be).
Most bars in Antwerp are rather good with a rich selection of beer. If you like reggae and afro, I suggest you check out Cool Runnings at the Leopoldplaats and Ile Afrique in the Aalmoezeniersstraat. If you like religious statues, check out 'Het Elfde Gebod' near the Cathedral. If you like fascists, go to the 'De Leeuw van Vlaanderen'. If you like techno and related stuff check out 'Cafe d'Anvers' or 'The Zillion'. If you like a medieval atmosphere, try 'De Pelgrom'. For jazz try 'De Muze' (Melkmarkt).
These are only a couple of names, but there are _lots_ more, so if you feel adventurous...
If you like good movies, go to the 'filmmuseum' or 'Kladaradatsch (former 'Cartoons'). If you like Hollywood crap, go to Metropolis or Gaumont. If you like good ganja take a trip to Holland. Try to tune in to Radio Centraal (103.9FM www.radiocentraal.be), a non-commercial radiostation with a varied, non-mainstream selection of music.
Update: Cool Runnings has closed. There's still plenty of world vibes here, though. Check out 'The Vibes' in the Hoogstraat or 'Het Zuiderpershuis' at the Waalse Kaai.
The Zillion has also closed. Still plenty of techno to go around though.
Well... Bars come and go here, but if you take the time to explore the night in Antwerp I'm sure you'll find something to your liking.