I found a free script, and it seems like it would be a pretty easy site to run, but how well do they normally do?
I made an extra domain into a topsite with a few widgets, it mostly serves to sweeten the pot on link deals. I like being able to offer an extra link without compromising the structure of the page. I don't think of it as any kind of mainline income, if that's what you mean. The traffic is light, mostly webmasters looking to list. It's an attractive alternative to a directory, but a little cheesy I suppose. The voting code annoys me, it seems very hyp-ee. One advantage(or is it) that Topsites generate lots of pages for indexing, a new one for each listing, and the sponsored listings get sitewide, even on admin pages. So that is where my other sites go. I use it mostly to advertise my other sites.