Will Smith calls it "the invention of the century", and I'm inclined to agree.  Since I bought my 15GB iPod in May, I've come to look at and listen to music in a whole new way.  I currently have about 2,300 songs loaded, and there's room for plenty more.  For a music nut like me, this thing is Nirvana.  (Oh yeah...I've got some of their stuff on it, too.)