My buddies and I are working on a Cube. We're all on Deckbox looking at each other's inventories for suggestions for the cube, but we're compiling the list on Google Docs. It would be way easier if there was a function to create a card pool pulling from our separate inventories, especially if it could keep track so we can remember who owns what when we pull it apart later on.

I like this idea, but I also now that it would take quite a bit of development time from Sebi to create it, which, quite frankly, is better spent elsewhere at the moment. In the meantime I suggest keeping a series of decks that are lists of the cards that each person has added as well as a deck that's a list of the cards that still need to be added. I know it's a little more tedious than you would like, but it fills the need that you have.