I've occasionally had some luck using baking soda (made into a paste with a little water, rubbed into the stains, and let it sit before laundering) on sweat stains. I've heard that adding a cupful of baking soda straight into the washing machine helps brighten things up, too, but I've never tried that. I'd definitely be afraid to use bleach on those fabrics.

I ruined many light-colored shirts before I realized my anti-perspirant use was contributing to the gross stains. Now I pretty much skip deodorant completely for exercise--I'm all sweaty anyway, what's the difference?