Stain Removal Experiment
My mom sent me this link to a DIY stain remover a while ago, and I finally got around to trying it out over the weekend: http://www.onegoodthingbyjillee.com/2011/11/goodbye-to-yellow-armpit-stains.html
2 parts hydrogen peroxide, 1 part Dawn, and a bit of baking soda. Mix it up, scrub it in, let it sit, then launder.
I found it worked as well as The Method (vinegar, Oxyclean, etc.) and was easier and quicker. It took care of collar/cuff stains completely. Yellow underarm stains were almost totally gone on the shirts where I scrubbed the mixture in, and on a few where I just rubbed it on with my fingers, it still lightened them quite a lot.
I mixed up a 3-cup batch of the stuff, used half, and stored the rest in a squeeze bottle in the linen closet for next time.
If someone has the link to the stain removal thread that has been mentioned here a few times, let me know and I'll post this there too.