True randomness doesn't always feel random. People swear up and down that their iPods, when placed on shuffle, favor certain songs over others.

This isn't device error, but user error. The iPod doesn't keep track of the songs it played before. After each song ends, it just scans the list and picks another track at random. Since it's ignorant of which song played five songs ago, that song is fair game...as are any other songs off of the same album or from the same artist. When that happens, the user detects a "pattern" that isn't quite there.

It's definitely happened to me. I only have a single song by the 1970's band Slade on my iPod, and yet it seems to play with a disproportionately high frequency when I've got my iPod in shuffle mode. I know it's just coincidence, but the part of my brain that's inclined to avoid black cats and walking under ladders suspects otherwise.

I'm really surprised that Apple hasn't made shuffle mode something that isn't truly random. Why not keep track of the shuffle play history and space out the tracks by artist?

The biggest challenge of technology, any technology, is to match its performance with the (reasonable) expectations of the user.