We do, we're founded on Open Source - but I guess we're special ;)
Anyway, this is not like a true answer to your question, but rather an answer to the "questions" in the other answers I guess. There are many ways to contribute to Open Source. Sure you can contribute code, but the other thing you can contribute is money by donating. Jeff Atwood (one of the founders of SO) did this a couple of months ago to a wiki system system I know.
When I worked for my previous startup we gave WatiN $300. This is a contribution, and probably a both a better (and at least cheaper) contribution then having one of our coders trying to figure out the code model and coding standard etc behind WatiN and then fix some bug and supply a patch.
But the THIRD way to "contribute" to your favorite Open Source project is more subtle, but often the definitive best way you can contribute which is by giving it attention like I just did with WatiN through that link.
I am willing to be $100 on that someone reading this answer will check out the link to WatiN, read about the project and download it and start using it in their own test suites. And they should since WatiN is a great Open Source project and Jeroen the guy behind it is truly helpful!
That is also contributing. Helping your favorite Open Source project get some attention by telling others how great it is!
