Rawtherapee is what I use too. I like tools that I can just point at a random directory, and get to work on. There are a lot of photography/image-management tools which insist on importing images into a "library", which ruins my filing-system.

I've got a photoshoot booked for tomorrow, so I'll try this out and see how it compares. (An average shoot for me results in 200-400 CR2 images to examine/reject/process.)