The main body that regulates "standards" in the USA is the American Psychological Association. At this point in time there are standards for using psychological tests (not on the web though) and they are developing standards for online therapy. I do know that they have met once or twice, but I am not sure that anything formal has been put to paper. My sense is that they are taking a conservative "watch and wait" approach to psychology on the web. Personally, I think that this is a BIG mistake. There are lots of exciting and controversial things happening to our profession in cyberspace and the APA needs to take a strong role in formulating what will and will not be acceptable, ethical and part of normal practice standards.
Anyone out there involved in the search for rules and standards for practicing in cyberspace?