Sims 2 doesn't have many mods in that department. For those Sims 3 has more and no doubt in 4-5 years Sims 1.5 will be getting stuff too.
My Sims 2 sims constantly get naked and have sex in a bunch of ways. The main mod I use is ACR. This does tons of different things. I haven't.
Pandora Sims contains The SIMS and other sim related games content that is child friendly Warning very naughty stuff and bad words are on this site. The final expansion pack (Due to the release of 'The Sims 2) for the sims which adult downloads for sims 2, default nude skins for sims 2. sims 3 sex mods, sims 3 sex.