I know I'm going to get pounded for this, but how about a sale similar to the Humble Indie Bundle charity sales? Ideally pick a good real charity. Yes Humble Bundle's are real charities, I'm making a joke about charities that aren't real :)  It could even be a community vote on the charity. Especially after any sort of disaster. If you look at the Humble Indie Bundle (not shilling, but really admiring their website design on designating amount splits) website, it's got sliders (as well as blank boxes) to enter amounts. Not only is this idea a good thing for charity, but (playing the devil's advocate here) it's good publicity.  

Also you could do an appreciation page (using the same design on the page) for just tipping the vendors. Maybe a vendor appreciation day? Odds are the first one would do better, but the second might be nice for vendors.

Something else that could be nice would be community voting on item creation. It could help vendors decide what to make next that might sell. If you have a vendor post image sketch ideas and put a poll on the page showing interest, yay or nay kind of thing. This could be a forum thread specifically for vendor suggestions and ideas. I do like the idea of the community (when it's not raising pitchforks) giving good input. *puts down pitchfork and hay bale. :)

Thank you for your suggestions! I will bring these up to staff :)

Thank you Kimberly. :) I didn't post a link because I didn't want to seem like I'm shilling a website. I do like their charity business model, and they have raised a ton for charity. I think this could be done any time, but ideally when there's some (this sounds bad) disaster, because people need help rebuilding.... Or if they are ill. You get the idea. I don't want to dwell on negative thoughts.

Edited to add the following

Oh also pet type charities too...