Try Craig's List (they're all over, but Arizona shouldn't be hard to pin down).

Ditto Craig's. I started advertising my houses there, whopping response compared to local newspaper. Since CL is free (for now) and reaches a much broader audience, I plan to continue to use it. The local paper generated only a couple calls and the ad was a whopping $120. I linked to it below.

There's also City Data forums. You can ask there if anyone knows of good places to live/rent/or seek housing online. It's very area specific. Here is City Data forums.

Here is a link that might be useful: Craig's List Arizona