If you hate lugging around a USB charger for your iPhone when on-the-go, the folks behind the PocketPlug have the answer for you. The PocketPlug is an iPhone case that has a built-in charger. The charging prongs lay flat in the case when stowed, but can be easily pushed out when your phone needs to be charged.
The only two downsides to this case is the fact that you can’t use your iPhone when it’s charging and that it adds some extra bulk to your phone’s form. However, if you value the convenience of a built-in charger and don’t mind these downfalls, expect to drop $70 for the case.