There is a partner site to modthesims2.com, called sexysims2.com, where there are a lot of nude/invisible clothing options for both The Sims 2 and The Sims 3, so if you have a chance to sign up for their site, they have some good resources... plus things like censor removers, anti-embarrassment patches, and patches that let your sims go to work in their normal clothing (so that your nude sims don't have to get dressed to go to work, for example)... you just have to sift through the sexual content to find it.