Just surfin' the web and i stumbled upon some songs that make you feel better. Although this link is to a spin off of the original-songs that make you feel better, they both seemed to accomplish the task. 8tracks also offers a variety of other music via radio streams and mixes. I've only spent a small amount of time on this site but it seems to be attracting a new set of songs to my ipod. Just give it a shot and let me know what you think!
p.s. The first link is to a website that literally changed my life on the computer. It takes you to random websites based on broad types of things you like. Give both of these commendable websites a shot!