With Vozme, you can turn any chunk of English text into an MP3 file by clicking one button. It's far from perfect, and isn't as clear as using the "speak" thing on my Mac (Oh, Vicki, tell me that you love me!) but it gets the job done quickly and easily, especially if you're supposed to be working and really want to be screwing off instead.
I just amused myself by converting a bit of my forthcoming Angel One review for TV Squad into a weird robotic voice.
Enjoy: Download mp3_angel_one.mp3 (136KB mp3 file)
(Vozme was found via Lifehacker)