I’ve been using GMail since early beta, and until recently I didn’t understand how to get the equivalent of a Outlook folder.  A coworker showed me how.  Basically you setup a label (folder name in outlook) and setup a filter and apply this filter to the label.  Combine this with this little tidbit of info, and you have a folder of unread messages.

http://googlesystem.blogspot.com/2007/05/shortcuts-for-special-gmail-labels.html