Oops...yes. Just open the App Store app on the phone. Click on Updates, then Purchased. You will see a list of all your apps, and you have the option there of downloading them to your phone at no extra cost. Some of the apps might be dedicated iPad apps, and in that case when you try to download it you are automatically sent to download the phone version.
My favourite photo apps are Snapseed, Alt Photo, and FotometerPro. I think Pinhole Assist will be useful when I get the Zero pinhole camera at the end of this month...