My main stalled project is Space Hulk. I made a great start on painting it when the 3rd ed box was released, but lost the face/body part of the marine with assault cannon and just kind of ground to a halt.
But I've become a big fan of the more generic rules sets and even wrote and published one of my own. I kept my LOTR stuff to play A Song of Blades and Heroes, and use Horizon Wars (my game) with 6mm and 10mm (perfect for RTT!). Now I'm working on a generic Sci fi skirmish system to put my old 40k and Dreamforge stuff on the table!
Of course, I also stalled with WMH, but that was because I really didn't enjoy the game, so couldn't be bothered to finish painting the army!