I got stung by something this morning - possibly a bee, I really have no idea - and did a MAD search for an antidote while in desperate pain (I was still able to walk so it really couldn't have been too desperate, but it was no fun) so I just want to record:

The most highly recommended home remedies were ice and toothpaste. And indeed it worked. I did ice first and followed up quickly with toothpaste, I could feel it helping right away, and a few hours later it's almost like it never happened.