Universal User Database for WordPress, PHPBB etc??

I have WordPress going pretty well I think (considering I only installed it yesterday), however I’m new to php, cookies, and everything else you use to do passwords and stuff for users.
I’m looking at having a forum, as well as a photo page (haven’t decided which program to use, either 4Images or Coppermine.. however is there a way I can give my users one single registration which covers them throughout all these aspects of my website?