Arm & Hammer Force Oxy Strength Pet Odour & Stain Remover works great on fresh stains. On old stains spray, let sit for a few minutes, then scrub lightly with a coarse brush and sponge off. It's cheap and doesn't strip the color.

 

That stuff works wonders. I've used it on ink, mud, soda, tea, something that was florescent pink (!?) It will take almost anything out in under a minute.

 

Spot Shot works pretty well... and its cheap too. Also, if a car wash by you has any hot foam upholstery cleaner, that works too. I use Spot Shot whenever I don't have time to go to the car wash.