Well, there's Gratipay (formerly Gittip), which is a great platform since it allows you to support an open-source project through regular payments. Unfortunately, the project has not yet received broad adoption, which I hope will change in the future, though.

Here's the link:

http://www.gratipay.com

In fact, there is a page for the Tor community, so if you want to support them, go there and give them some money ;)

https://gratipay.com/for/tor