User Accounts

[eluser]Michael Wales[/eluser]
Most of those authentication packages are easily extensible to include whatever extra data you'd like to store (or you could make a new profile and link them by unique IDs).

I believe these forums are part of Expression Engine - so, technically, if you purchased a license to EE you would have the code.

Honestly, managing users isn't that difficult though - it's basic CRUD with your database.