I just recently stumbled upon this new website called Thankslot that gives out free downloadable Thank You cards and blank cards as well. It's a fairly new website (I believe it started in March since that was the first post) but it's got a lot of great potential to grow. Above are two examples of my favorite ones by them.
This is great if you want to DIY your own thank you cards after the wedding. Hopefully you won't be in the negative after your wedding. If so, here are some free cute thank you cards to give out! Plus they have a great instruction tutorial on how to print these out.