Just Relaxing 3.5 is designed to help you relax during those stressful days, and its catalogue includes a series of relaxing sounds like waves, birdsong, wind, etc.
Certainly, after listening to it for a while you have a very pleasant sensation, especially if you`re having a hard day. The only downside is that this is a shareware version and so has a very small sounds catalogue, but it is still worth it.