Stay On the Straight and Narrow With This Three-Point Laser Level
by Shep McAllister on Kinja Deals, shared by Tercius from Lifehacker on (#46F1J)
It's probably overkill for hanging a few pictures, but if you're doing more serious DIY work around the house, this three-point self-leveling laser can project perfectly straight vertical and horizontal lines across any wall, and it's down to $89 today with promo code OWQZHZ3O.