I would love a feature where I could see all of the cards in a particular set, and have a checkoff box, or a "have in inventory" field. That way I could keep track of all the cards I need to complete a set. It's basically possible to this already, but you have to create a new "deck", and input all of the cards manually (not a big deal to me), the dealbreaker is it organizes them by creature, sorcery, land etc... like it would if it were an actual deck.

Also, iphone app would be real nice.

Maybe pricing pulled from a website of your choice? That sounds kind of hard to do though... Just a thought.

Other than that, great job I love this website it is helping me organize tremendously!

You can do this through the Card Database and its Filters (Advanced Search).

For example, here is a list of all of the Avacyn Restored cards, sorted by Name.
The left most column is how many of that card you have in your inventory, and you can also sort on this column so that you can see which cards you do not have yet.

That's great! Thanks for the reply.