I love the addition of Collections to the database. My suggestion is that there
should be some form of quick add when you click on the pop-up of the minifigure
or part. It would save the extra step of navigating the product page and inputting
it in your collection.
Another suggestion would be to have some sort of check mark when you look up
pieces and figures in the database, so you can make a quick determination of
what you have in your collection and what you still need. An example would be
looking up Avatar minifigures and seeing that you have 6 of the figures in your
collection (and if you wanted to complete your collection would need to get the
rest).