For those who still wear synthetics, pop a dose of borax (20 Mules Team, I think in North America) into each wash. It's a naturally occurring product mined almost exclusively, I understand, in western US, and it is used as an antifungal/bacteria agents in stuff like home insulation.

The borax you buy in the supermarket is specifically for laudering, and it is relatively cheap. When I wash my jerseys with it and regular laundry powder, there is no smell. When I miss out on putting borax with the wash, the sweat smell returns.

Machka and I have had really smelly stuff that's got damp while camping or that we've changed out of during long distance events, and they have come up trumps with borax added to their wash.