Here are sites I've heard of but haven't tried.
-Free Realms
-Jump Start [for younger people]
-Habbo
-Sims [I've played video game versions but not pc versions]
the sims 2 is a really really good game, but it's not from the internet, but you buy it at a store and install it in your computer. probably you've heard of the sims 3, but i think sims 2 is better.