Can I download older versions of apps? I've got a 1st Generation iPod with iOS 3.1, and I'm frustrated because I most apps don't run on such an old iOS, but I can't put a new iOS on. Is there eny way to get old versions of all those apps?
I'm afraid not. You can keep running old versions of apps, but you can not download them. For example, Check the Weather was recently updated to require iOS 6. If you have an iOS 5 device you can no longer purchase it on the device, but I can keep running the version I have as long as I don't delete it.

I understand and share your frustration.