Long-exposure photo of two people having sex on a bed. (It's mostly safe for work, believe it or not.) This reminds me of two things: the timelapse threesome scene in A Clockwork Orange and Jason Salavon's work, specifically 76 Blowjobs and Every Playboy Centerfold. Those last tow links probably NSFW. (via the h line)
Update: Atta Kim's work is similar too, particularly his "Sex Series". (thx, jeff)