Sim Stuff:  

 Sapphire Sims2 An interesting site for Sim Mods - aliens and lots of lovely color

SIMS 2   The official website

 Mod the Sims A collection of Sims mods      

 XMSims  Very beautifully designed outfits, etc.    

 2 For U - more Sims, lots of meshes

 inSIMenator  More good SIM stuff, merfolk