Makeappicon: Generate Application Icons Easily
Makeappicon is a free and web-based tool for generating app icons quickly.
It works by simply uploading a big-sized image and the app auto-resizes it to the required dimensions.
The sizes are the ones that are required by iOS + Android apps.
Makeappicon accepts .JPG, .PNG and .PSD files (works best with a 1024*1024px image).