Along with stalking our salsa garden, I made a new cheap city chick discovery. Diluted hydrogen peroxide (3%) - 2 tablespoons per quart of water - does something fierce to plants. Bill Munro wrote an article about it way back in January 2003. Here's yet another article from the Dirt Doctor website that details the benefits and hazards of using hydrogen peroxide in the garden and around the house.
Just remember that too much of anything is bad for you and your plants. Unless there's some fungal disease outbreak, I'm going stick with soaking my seeds in the solution for a few hours (been soaking them overnight) and otherwise limit use to once every three months or less.