Josh Groban:
the official website, the place is crammed with news, chat transcripts, fan forums; it's an awesome site, and lives up to its status as 'official'.
RollingStone.com - Josh Groban Main:
Rolling Stone's Groban site, with great fan resources.
Josh Groban Fan Site:
a site in progress that looks promising (and is enough of a resource in its present state to satisfy immediate curiosities and still keep you busy for a good long time).