I own a Line 6 Spider III 15 watt 8 inch amp (which I like) however, I find it a real pain in the you-know-where having to press the different channel buttons to change from the clean tone to the metal tone. I play a lot of Metallica stuff, and it becomes really annoying having to reach out from my guitar, especially on songs like Fade To Black and One where there a plenty of changes between cleans and heavies. Is there some kind of foot switch that I can buy which will let me change between channels with my feet, or am I going to have to keep going on as I am?
Not only is the Spider III 15 not compatible with foot controllers, its not compatible with musical instruments.

actually no there is no foot switch for the 15 watt. you'd have to get a bigger version
I wondered why the frisbee was getting bigger, then it hit me.
I read on wikipedia that Eddie Van Halen used line 6 spider III amps awhile ago...

but it got deleted so it may have been a lie