Glory
You'll be in charge of your own message, so there's a lot of leeway when it comes to glory in the world of YouTube personality-dom. If you happen to rise to fame by spreading an uplifting message of joy and peace, then good on you. This is going to be easy.
What's more likely, though, is that you rise to fame by cursing at poorly made Flash games. If that's the case, you'll need to use your visibility for something else if you want to start banking those warm fuzzies.
If there's one thing charities love, it's inviting every A-list, B-list, and heck, all the way down to J-list, celebrities to their functions. And, often, celebrities love it. It's a free dinner, looks good for St. Peter, and so is pretty much a win-win. If time is of the essence, you could always just donate cold hard cash. The charity will probably like that even more than having to fly you in for a banquet.
Whatever you choose to do, the point is there are plenty of ways to do good and feel good when you're famous. But you'll need to make an effort to find them.