Actually, I'm really no good at practical jokes and the only April fools prank I ever remember playing was when a roommate and I dipped cotton balls in chocolate and delivered them to our friends in the neighborhood as homemade chocolates. Greg still hates me for that. (He's pretty sensitive about what goes into his mouth. . .)
I haven't done anything today, nor will I, but last year I pulled a prank not on April first. And it worked out pretty well. Or pretty terribly, depending on how you look at it. If you want to read about it you can go here, and its pretty easy to see how bad I felt about it by what I wrote.