Editor's note: This guide was written about an older version of iTunes. For details on linking your iOS devices with newer versions of iTunes, see our story here: How to use home sharing on your iPad, iPhone, or iPod.
Sync iTunes on multiple computers
I have no idea how many MP3s I own. It's not that I'm too lazy to look--the problem is that my collection is scattered between all the computers in my life. I have a few albums on my personal laptop, a few more on my work laptop, and the bulk of my collection on an ancient Apple G4 desktop at home.
In a perfect world, I would have the time to fill the gaps in all my fractured collections, making the iTunes experience the same on all my computers. Until recently, though, Apple hasn't made it very easy to copy your music around. While iTunes still forbids you from copying music to your computer from your iPod, iTunes 9 finally acknowledges that law-abiding users need an easy way to share media between multiple computers in their home.
To this end, iTunes 9 includes a feature called Home Sharing that allows up to five computers on a local network to manually or automatically transfer iTunes media back and forth. Personally, I wish Apple would have come out with this feature before I'd sunk my time and money into an ill-fated attempt to get iTunes running on a home NAS drive, but hey, better late than never.