Using this library, ZXing, we have a project at school in which we'll implement a inventory system using Android phones.
We aim to use an Android phone to be a inexpensive replacement to this:
I've read some of the warnings on the FAQ for certain phones. Is there a specific phone that Android developers prefer (with use of the ZXing library in mind)? We have to buy the phone ourselves, so we would prefer not to buy the wrong phone!
I don't know that there's necessarily a "preferred" developer phone, but the Nexus One is the official developer phone as endorsed by Google: http://android.brightstarcorp.com/index.htm . Despite being kind of a business flop, it's a very nice phone, and it's hard to imagine how you could go wrong with it for development purposes. Since it's put out by Google, it should support everything there is to support, and it's not mentioned as having any issues in ZXing's FAQ.
Developer here. The single factor that really makes barcode scanning easy is an auto-focus camera. Resolution, CPU, etc. don't matter. The library can work with any version of Android but 1.5+ is recommended.
So, just about any used Android phone ought to be fine.
Follow up at http://groups.google.com/group/zxing .
You want phones with auto-focus capability on their cameras. Some of the smaller/cheaper phones, like the HTC Tattoo, have fixed-focus cameras. Some tablets do not have a camera at all. Most Android phones have auto-focus cameras, AFAICT. Certainly, every one I have used has had one, and I have quite the collection at this point.
I'd watch out for phones running Android 1.x, not because of any ZXing problems, but if you are going to spend money, I'd invest in an Android 2.x device. One advantage of the Nexus One cited by Blumer is that it will get new Android releases as fast or faster than any other device.
Beyond that, and beyond specific problems cited on the ZXing site, anything should do, if it works with your carrier, is a color you like, etc. :-)