David and Toby look at (among other things) the recent Snapshot's "Minecart with Command Block", which combines all the functionality of a command block with the sleek portability of a minecart. Sweet!
SCRIBBLENAUTS: A BRIEF LOOK
Speaking of free-form building, have you seen Scribblenauts? Imagine combining any words you can think of, and having that thing appear in-game for you to use in problem-solving (or starting)! Pretty neat, and definitely worth a look. There also might be a free giveaway of the game, and/or a free 3DS to be had as well...