One interesting thing regarding the whole internet revolution and music is that every band now has a website. While the band websites at Myspace are useful for promotion they are somewhat limited.
If any band wants to make make money online they need to create their own website. The design of Myspace is really all about the owners of Myspace making money. Sure the bands receive some promotion which should lead to more income downstream. But by combining a Myspace website with another site any band can go after two different targets.
A good bank website would obviously contain band bios and touring information. To make some cash the sale of cd and clothing can easily be included. You could even link your site to an Ebay store that would make the transaction easy.
Another way for a band to generate some cash is to make money blogging. While that might seem to be the first choice for many acts the benefit would be that it would be very easy to update the site. Even when the band is out touring it would only take a few minutes everyday for someone in the band to write quick post. Stuck at the airport or in customs at the border? Blog time. The fans will love it. The website simply has to contain some Adsense or Adbrite so you can generate a few extra dollars. People will likely click on the ads if they are displaying the right type of ads. The ads should be highly targeted so the click through rate should be quite good.