My iPhone 3G crapped out on me a couple months ago. Had it since they first came out, so it was kinda old as far as technology goes. Became super slow when doing anything, especially the "smart" stuff like GPS, and eventually stopped taking a charge. Replaced the battery, the connector for the plug, etc. and nothing helped it.
Now I'm using an old brick my buddy had laying around... gonna eventually get another iPhone to replace it.