Will,
I'm using VisualMill. It was bundled with my ShopSabre CNC router.
Although I've watched other people use programs like MasterCam and SurfCam, this is the first CAM program I've ever used. It's the basic version, and it's served me well so far. There's a few things that it DOESN'T do, but from what I've heard, the "pro" version offers more functionality.

I checked out your Flickr files. Nice stuff. Do you work for an ID firm?

Johnny 501
KOZM Guitars