Tide Stain Release might just be the best thing since Tide! LOVE LOVE LOVE it!!!
It's meant to be used in addition to your normal laundry detergent, and it works wonders to remove all of those tough stains that I normally would have pre-treated or even tried to bleach out. I really love the individual use pacs, though they have a liquid version and even a powder version if you prefer that. It definitely works way better than Oxyclean AND you won't accidentally bleach your dark items like you sometimes do with Oxyclean!
I greatly recommend this product for all of your tough stains, and even just really dirty laundry.