Apple offers their own advertising-friendly estimation of how many songs each model of iPod can hold, but those numbers are based on fairly unrealistic standards of 128Kbps AAC songs that are a mere 4 minutes long. Toss in a few tracks from Phish or Beethoven's 5th, and you can easily hurl this song estimation into the realm of 'anyone's guess.'
Enter iLounge's iPod Storage Calculator, a handy little web tool (what, no widget?) that lets everyone from newbies to demanding audiophiles perform some quick calculations to figure out just how many songs, even at varying bitrates, their iPod can hold.
As a matter of fact, the only thing about this calculator that makes it iPod-specific is the handy pull-down menu offering one-click access to every storage capacity the iPod has ever packed; in other words - anyone can use this tool to get an idea of how many songs they can bring along.