MPatcher - running shell scripts on Android®, but the most common use is to apply custom patches to decompiled packages (can be directly launched from within APKTool M as well).

Key Features:
Execution of shell scripts
Running shell scripts as root
Execution of scripts with the ability to pass the path to the file/directory as an argument
Creating scripts/patches directly in the program
Import/Export Scripts
Display the results of the script in real time
Works in conjunction with APKTool M