I have been playing a couple rhythm games for a few years now. Guitar Hero being one I'm sure most have played or heard of. Others are Stepmania and Flash Flash Revolution, which are both arrow based, like DDR, but for your fingers and a keyboard! My best friend showed me this a few years ago, and I have been getting better and better!
Flash Flash Revolution is actually a browser flash game open to the public to compete by ranking song scores for over 750 songs, grand totals, songs played, out of what is now 1.7 million members. I am rank 447 by grand total. But if I included the time I played Stepmania I would probably be fightin for at least the top 100 XD.
I challenge you to give it a shot! FFR The Game FlashFlashRevolution.com
If you click the S under where it says "Genre Select", a list of all the public songs will appear in which you can list in order alphabetically, or by difficulty ranking from 1-13. You tap your arrow keys as soon as the corresponding arrow reaches the top. You can change the speed of arrows for when you get to more difficult songs that would clump the arrows together and make it very difficult to read. You can also change what keys you can use to hit the arrows. Instead of Left, Down, Up, Right... I use S F J L, respectively.
Here are a couple replays I have gotten over the last few days...