The original iPhone can only be updated to run version 3.1.3 of iOS. This means that the vast majority of apps in the iTunes App Store can not be loaded onto the original iPhone. It would be nice if Apple allowed developers to keep old versions in the App Store for people with old devices. But since they don’t, it’s great that you can jailbreak the phone to allow many apps to run.
I followed these instructions from iPhoneBlogr. This not only jailbroke the phone. It also unlocked the phone so that it could be used on non-AT&T carriers, especially useful if I want to use the phone when traveling abroad.
Then I restored the phone in iTunes using Whited00r 5.1.
Whited00r gives you a new app store with a links to older working versions of Skype, Twitter, Facebook, etc.
Performing the jailbreak can be a little scary for some people. But if you have your iPhone 2G or original iPod Touch in the closet or ready to go in the trash, give this a try. They are still good devices if you make the Whited00r updates.