With all the hype around new products, sometimes it’s easy to forget that Apple is also pretty good at making features that are just plain old fun. Tonight brought the perfect example: iTunes 8.1‘s new “iTunes DJ” feature.

iTunes DJ is the new name for “Party Shuffle” in previous releases of iTunes. But now it’s actually a useful and fun feature when paired with iPhones or iPod touches. And you’ll notice I use the plural of those words.

You see, here’s how iTunes DJ works: In settings, when you click on “Allow guests to request songs with Remote for iPhone or iPod touch,” it will enable all iPhones and iPod touches with the Remote app installed to find your iTunes Library. When those guests set your library as a source, they can then pick any song from your library to play next.

You can even set a custom welcome message for would-be DJs at your party.

But the real fun comes when you enable voting on songs. If you’re at a large party with dozens of iPhones (not only is that not out of the question here in San Francisco, it’s downright likely), the next song can be crowd-sourced by popular vote. This way, no one can sabotage a party by selecting “Who Let the Dogs Out?” or some lame slow song by The Eagles.

The one downside is that for this feature to work, you will have to give partygoers access to your WiFi, so they can find your iTunes library. But it’s not that big of a deal to remove your WiFi password for one night, or use the new guest options that Apple AirPorts and Time Capsules offer. You can also set a password for the iTunes DJ feature if you want to limit access to only some partygoers.

Yes, Apple has just turned iTunes into a social jukebox.