There are few more beautiful sounds in the world than a pedal-steel guitar played by a competent musician. I once played in a band with a pedal steel player, and tried to figure it out myself. Couldn't do it--and I'm almost always able to get something reasonable sounding out of almost any instrument you put in front of me. It's not just the way the pedals work, but also the way you have to rest the slide against the strings to create the notes.
This blog entry explains how it works. More sensible than the Mellotron, at least.