A payment of very small sum of money.
Micropayments are often referred to when discussing prices of immaterial things, such as the files in the Internet. Basically, the consumer might pay a small sum to download a file.
The problem is the money handling, as banks don't like charging small sums directly from bank accounts. Setting up "accounts" at the shops is often unfeasible and requires extra hassle.
There have been some solutions to this sort of problems. Digital money has been one suggestion. In Finland, EUnet tried using DigiCash, but it had one serious problem - there was an infrastructure, but no "products" to sell.
The micropayments are becoming a hot topic of debate again - particularly what comes to "legal alternatives to Napster". With a working micropayment scheme, downloading music could be interesting. Some music selling services (like emusic.com) use fixed monthly fees, though.
Currently, in Finland web shops use SMS messages for micropayments - an example of a feasible micropayment system in a country with large cellphone user base.