I keep anything that needs my attention in my Inbox and move everything completed to my Saved Folder.
I have just started using Categories as of Monday and I think they are something that more people need to be aware of.
I have a few rules which detect Project Names from the Subject and auto assign to the correct Category with my Inbox set to Group by Category.
Finally I use Google Desktop for Searching - much quicker and easier although does not like me moving my messages to my Saved Folder.
