check out the SEO4SMF mod
This is almost what I want.

but the userprofiles are not available under
http://www.domain.com/usernameSEO4SMF does:
http://www.domainname.com/profiles/
Username-userid.html
As far as I can read for this mod on the owners site, it was not possible to hack profiles and -userid in the link out, because this mod doesn't use any database modifications..
In my opinion: username.domainname.com (mod_rewrite with a dns subdomain wildcard) or
www.domainname.com/username are very usefull for accessing a website. (especially community website's with extra userprofile options enabled).
