Android (4.1+): Focal, the camera app from CyanogenMod, is a powerful photo and video-taking tool. You used to have to flash the whole ROM to get it, but thanks to its developer (and a bit of drama), the app is now up on Google Play for anyone to try -- assuming your phone supports it, that is.
Focal brings multiple photo and video shooting modes to your phone, including burst, timer, and scene modes, HDR mode and photo filters. On devices (specifically Sony phones) where shutter speed is an option, you can control it.
Focal also includes a built-in panorama mode and an open-source replacement for Google's PhotoSphere, so you can stitch together 360-degree shots if you want to. The screen is clear and open, and you can swipe in from the sides to pull options and widgets in to change your settings. There's even a handy photo drawer you can use to review your recent photos without having to leave the app and open the gallery.
Focal is currenty in beta, and the developer behind it points out that he's working on support for newer devices, so older phones may not work well with it right now.
If you liked the camera app from CyanogenMod and want it on your current device, or you just want to see what the fuss is about, grab it from the link below.