I use www.vgcollect.com like DorkOverlord. It's the best video game database website that I've found. You can create collection, wish, sell and now playing lists. If a game you have is not in the database, you can create an entry for it. You can write notes about your items, date purchased, cost, and it has a checkbox you can use to designate if you have the cart, case, manual and other inserts. And once you created a list on the website, you can export that data into .csv format. It also has a forum for discussion or questions on how to use the database.
My collection is here so you can get a feel for how it looks. I like the interface more than any other database site I've seen.
If you can beat vgcollect, then I'd say you would have one of the best game databases around.