What apps will work on the iPhone 1st generation 3.1.3?

I just traded my iPod touch 3rd generation for an iPhone 1st generation. While thinking this was a good deal, I didn't know that I wouldn't be able to get any apps. This iPhone has iOS 3.1.3. Any help here would be greatly appreciated. Also, if I jailbreak the iPhone, would this work to get all the apps I want?

If you update it you should be able to get all the current apps, and I don't think jailbreaking it would allow you to get all the apps you want only certain apps not from the app store.youtube has a tortorial for jailbreaking if you want to go that rout. I believe there's a software program called black magic? I'm not sure new ones are being created constantly