You need to redirect people to HTTPS, and your credit card form should have a secure lock icon as well as icons for the credit cards you accept. You should have a little promise on your form like "Your credit card information is encrypted for your protection by Industry-Grade 256bit Encryption and will never be shared."

As far as the rest of your website, for me personally, I trust websites that are polished, simple, and have professional copy. I was really impressed with Swipe.com recently and immediately trusted them.

Shouldn't that page say to whom I am giving money?

I think it's a nice concept. People will perhaps be more inclined to give if there was some sort of feedback mechanism. Something that will tell a complete stranger that the guy who was an ipod shuffle for his birthday deserves my $5. Perhaps if I knew that this guy gave $10 to someone else last week for a school textbook? Just thinking out loud.

I cant believe I missed that. Thats a very good idea.

I like the social integration

Will you do me a favor and check out my startup here too: http://news.ycombinator.com/item?id=3073337

Thanks