I use an excellent and inexpensive text-to-speech program called TextAloud for proof reading as well as for many of my other reading tasks. I find that my ear very often will catch mistakes my eye has missed. Here’s the link:
http://www.nextup.com/TextAloud/
I’m with you there. I’m a writer, and I find that if I read the text out loud to myself I catch all kinds of stuff. Reading the text backwards also helps catch items otherwise missed. That is, read the last word, then the second to the last word, etc.