check out http://forums.digitalpoint.com/forumdisplay.php?f=29 you will probably find something useful there
I've actually thought about this alot myself. I would be up for sharing info if you'd like to shoot me a PM. Are you curious, or are you actually looking to start one up? In my findings, it seemed though it would be difficult to find the levels of profitability you would require, although I did get quite far into the planning process. I would also like to ask you a few questions about the finance site in your sig link - I find it a very interesting idea, and would be curious as to your experiences with the service.
Without a few more details it's hard to answer this properly. Once upon a time I was the sysadmin for an ISP. You need to think about the services you plan to offer You need a way to suspect accounts who don't pay You need to make creating/suspending/deleting accounts a "clerical" function. You need someone to offer technical support to clients You need someone to fix/maintain/patch the servers You need a way to bill/track usage of the services you offer Just for a start.