Here’s a tip that’ll save you some money at the App Store: When downloading an app, do it from your computer rather than through your iPhone or iPod Touch directly. What’s the difference?

Well, it so happens that there’s a little problem with the App Store. It identifies you as a unique customer by your iTunes account–not by your device, and certainly not through a combination of both.

What it means is that if you download an application–whether free or paid–through iTunes, you can sync in with your iPhone as well as other iPhones or iPod touches–without paying anything extra.

We’ve been used to the per license, per install payment method when using software applications. But the App Store is strikingly different: it treats your apps the way it treats your music. Once you’ve paid for it, you have the freedom to decide where and how you want to use it.

I’m not sure how long this will last. but unless Apple changes this–or at least sets a limit on how many devices can sync with one iTunes install or account–I can well imagine unofficial “App Stores” coming up in all corners of the world-little booths with a couple of computers maned by a single person who will sync your iPhone and iPod touch, put any apps you want on it, and charge far less than the App Store itself.