Well the site is simple, but what you are asking is simple. I've seen this done beofre. Some girl paid off all her credit cards by doing this. I think it was over $50k. Now she uses the site to help others in debt.
You can't really see the 240 or .com on the banner. It blends in to the background. Brighten it up.
Maybe you could have a picture of your dream car that you are trying to raise money for.
Maybe to help get you more money, you could ad some google adsense.
Good luck.