Although my shelters aren't advertising it this year, many rabbit rescues and shelters build little care packages during the holidays to bring to as many shelter rabbits as possible. These usually consist of such things as a paper bag filled with hay, paper tubes and popsicle sticks. It may not seem like much but for many buns it is the most exciting thing they have seen in quite some time.
If you know of a shelter nearby, you can find out if they are doing such a program and a simple donation of paper bags or tongue depressors (I find them at art stores) can go a long way. If they're not, and you have some spare time and a little extra cash, you could ask them if they would mind if you dropped off some care packages and make them yourself at home.
Of course, a simple monetary donation is always a happy present. Note that this is from the 2008 drive. I can't seem to find one for 2009 with the HRS.