There were pianos with five pedals at one time, Conrad Graf's Fortepiano:

[originalpckelly]

http://www.youtube.com/watch?v=5omX2JM1qT8&fmt=18

Don't mind the rambling in French, read the text at the side. It's really interesting how beautiful these instruments sound. I love the moderato pedal, which is what the person who posted the video said was "engaged" at the beginning of that video. I wonder why they don't have those on modern pianos?

For those who may not know, a fortepiano refers to the classic version of a piano, in many cases without as many strings or a metal frame to hold the strings. The Graf fortepiano does indeed have a frame in it, and it appears to have a second soundboard as well.

Unfortunately, I cannot find more information on this instrument, it appears very little is available on the web. :-( Just this video and few others.

[MineralMan]

1. Google just fortepiano, and you'll find a wealth of sources...

Graf was a maker of the instruments. There were many others. Start with the wikipedia entry, then branch out.