There are several anime series that have scenes with characters that are nude, or nearly so. For those that have been shown on American broadcast television (such as Tenchi Muyo!), a digital editing technique was perfected where the offending characters are given a digitally created swimsuit. Also, characters that are revealing more than they should might just recieve a few digital alterations - Nagi had her swimsuit edited in the contest in one episode of Tenchi Universe, so as not to reveal as much. (What, you thought she won the contest on personality?)
While some people tend to decry the use the digital bikini - and almost everyone wishes that it wasn't needed, the reality of broadcast censors means that if we want to be able to see some of these shows on the airwaves, we're going to have to accept the use of such ploys.