Simsville. It was supposed to exist as a middle ground between the city management level of Simcity and the household portrayed in the Sims. Basically a neighborhood simulator. You'd be able to import your Sims into it to populate your neighborhoods and then give them stuff to do by creating coffee shops, movie theaters, parks, etc.
I was pretty obsessed with The Sims and Simcity 3000 at the time so the idea of having a third "Sim Pillar" was very appealing to me. I'd often check the website for news.
Unfortunately the game was cancelled in 2001, probably because it'd be made redundant by the extended neighbourhood features in The Sims 2 and according to the people who played the E3 demos, the game just wasn't fun or interesting to play.