if your server supports htaccess files, you should be able to do something like this through a simple redirect. I have used it to spoof user and keyword subdirectories, so you could probably do subdomains if that was your thing.
You'll see what happens to the address bar when you click this link. htaccess turns the path /user/AutomatikStudio into a search on the term AutomatikStudio:
http://pictures.bonsaitalk.com/user/AutomatikStudio
Unfortunately, this did not make my forum the most popular on the Internet, however the latest stats indicate we are running a close second.
Regards,
Matt