I've always been fond of map editors. I've spent my fair share of time inside of the Half-Life 2 Hammer editor, the Torchlight map editor, and have very fond memories of recreating the classic Team Fortress map 2fort in TimeSplitters 2. Although I've never created anything truly spectacular, there's just something magical about seeing your creations come to life.
Legend of Grimrock developer Almost Human has released a video demonstrating their upcoming map editor, and lucky for us, it looks incredibly easy to use. In fact, it looks a bit too easy to use. Naturally, I assume some sort of magic is at work here. It's in 2D, lists everything out for you, and allows you to preview your work immediately. Heck, even programming minor looks easy! I can't wait to dig in and start playing around with this. I look forward to what crazy things the community can come up with.
There's no set date yet, but I think I speak for all of us when I say "the sooner the better!"