I just recently was told I should tell people about some of the little things that I use on my computer that "normal" people don't know about.
If you like music.... never have enough new or old tunes check out LAST.FM
It plays music based on an artist or a style you tell it you like and it does a great job of learning your tastes. I started with U2 and was not surprised that it found a bunch of similar music - Sting, REM, etc. But, when I went back to my obscure tastes it found knew - The Prayer Chain... and suggested other music that I loved back in the 90's
You don't have to create an account to test it out, but if you do it starts to remember you tastes and make your own stations. I think I'm going to add the Facebook app.