I've searched for the answer to that question, but so far to no avail.

Hopefully someone who knows the answer will reply to your post.

About 6 months ago, I came across a tool that was still in Beta called SpyFu that did essentially this (though I was using it to find the keywords of my competitors).

The data wasn't spot on and there were a few keywords listed that were obviously unrelated, but I was happily surprised and impressed with what I was able to learn. Hundreds of keywords for both organic and paid (which I promptly loaded into AdWords). I believe they have started charging for their service but it should be very affordable.

I tried spyfu but don't see how i can search out what my pages are ranked for. I want to see what keywords in Google, MSN and Yahoo does my page say [123.com...] rank for (or if they are even ranked. Any recommendation?