Rosalind - 1:30 pm on Dec 10, 2012 (gmt 0)
I've shut down a few sites over the years. If you shut it down sooner rather than later you can redirect that drip of traffic to where it's more useful to you. You may also be able to salvage certain sections or types of content. Just look at what's giving you the most hassle, such as UGC or free tools you don't have time to provide support for, and transfer the uncontroversial money-making pages to other domains.
It wasn't until I closed down one of my websites that people came out of the woodwork and told me they'd miss it and it was a shame I wanted to close it. Up until then I'd got more negative feedback than positive. People don't appreciate free until you take it away.