My FI and I are doing rock candy in our wedding colors. One of the groomsmen has sworn to vigilantly pick up any rock candy left behind.
As for the donations thing, I'm really not a fan. Not that I'm against donating... I'm against donating and then telling everyone you know about what a great thing you just did. I think that should be more of a private thing. Additionally, there's no such thing as a charity without controversy... you really don't want a guest leaving offended because you donated to a charity that they're very much against.