What PPC Bid Management Tools Do You Use?

In a Google Groups thread, AdWordsPro Sarah has asked us what our favorite bid management tools are. There are a two different tools represented thus far, and it's interesting to see what you've got to add.

One user acknowledges that he likes Google's tools (which fortunately are free).

Another is using SearchRev.

I'm going to mention that I saw a demo for Acquisio's tool back at SMX East, I think, and it looked mighty fine. (I don't use any tool right now since I don't really do PPC regularly, but if I had to pick something, this would be it.)

What tools do you use?

Forum discussion continues at Google Groups.