Find out if martial-arts studios in your area allow people to observe classes or go behind the scenes at a tournament. Look up road races near you and let the sponsors know you have a group of eager potential volunteers to work at the finish line. 'cause it's one thing to put ideas into heads, and another to show the possibilities that exist. And neither of these outings would cost any more than money and time.
Browse around on detroityes.com. I know I read something there a while back about a non-profit boating group that operates out of a classic old clubhouse. Bringing crew, kayaking, etc into the lives of city kids is their reason for existence. (I know Warren technically isn't the city, but it's not suburbia either - we understand each other, no?)
The key thing here, as has already been stated, is to get kids comfortable in the bodies they were born with and give them a firm foundation for happy healthy lives. And it's no less important to open up the world of sports beyond the endlessly exposed football, basketball, and baseball. (That the NBA is heavily AA while the NHL is 95% White is no accident, neither is the fact that you rarely see Blacks taking part in stuff like water polo or snowboarding. No matter what shade you are, if you never see it on TV or know anybody who participates or see a place to learn it, it might as well not exist.)
I know exactly what the OP means about the letter he received. I've gotten a few, always unexpectedly, after throwing energy into backing a program in a "minor" sport or putting a virtual arm around somebody's shoulders as he fights the good fight to come out. You do something 'cause it's the right thing to do, hope for the best, and leave it at that. Most of the time that's how it winds up. When it doesn't - and you're hit with one of those soul-baring letters of gratitude - it blows you the fuck away.
Best o' luck!!!