For general pictures, no HDR, Camera+ is pretty good. It handles action shots fairly well and allows for separate exposure and focus control.
For HDR I use iCameraHDR, it's a simple interface and let's you focus where the dark and light areas in the frame are so you can sort of control the amount of over and under exposure.
I also use Hipstamatic for the antiquing effect, but I also have Photoforge2 with the Pop! Cam effects package for a similar effect.
For panoramic shots I have Auto Stitch, you take independent shots and import them to the app and it stitches them. They suggest a near 1/3 overlap for best effect and it works pretty good, I tried the Microsoft app and it really sucked.