Gtalk by Google works well, even has the option of "going off the record" if so wished, so that communication will not be stored on your other end that you are talking to, otherwise both of you can go into the thing and 'view past chats'
However, there are some people that might be called 'paranoid' or 'overcautious' that constantly worry about big brother checking out random email and communication of other sorts like Gtalk.