It runs on my personal sims-family.net server.
However we have looked into hosting. "Host it for you" places are typically not going to work for us, since we need the ability to set up mailboxes for the forums, pop, smtp, plus php and mysql for the database. They're also a pain to use, as I'm making changes all the time, so having access to all the php settings and controls is important. Also having the database stored locally is important as we're always tweaking the data structure to add new features.
Then the cheaper ones end up tacking on ads.
Preferred solution is to get into a datacenter... Then we get guaranteed bandwidth and uptime, and have negotiated down to about $100/mo but that's still a chunk of money to put out.
If people have good revenue-building ideas out there that would not be impacting to the function of the site, not encumber the users, yet offset some of that cost, let me know.
-mike