I learned about alternate tunings from Johnny Rzeznik.  :)  I was first learning to play guitar under his direct inspiration, and I could not for the life of my figure out how he got those sounds out of his guitars.  I assumed I just would have to learn to play better.

Finally, a light came on.  He rather frequently does not use standard tuning.  Bingo.

For a while I was really getting into it, but it's just too much work to change my guitar's tuning to play a specific song.  So, I've tried my best to work the "sound" of alternate tunings into my standard-tuning songs.

Hmm, I didn't mean for this to be about me, though.

I love Johnny's songs.  Iris, the one he is probably best known for, is tuned BDDDDD, I believe.  I learned it at one point but have since forgotten.  :)

He does guitars as well as most of the vocals and songwriting for the Goo Goo Dolls.