Banana Patcher is able to apply on-the-fly Preloader patches to System Menu without installing anything to the NAND. Some of the code was taken from Waninkoko's Menu Patcher.
Useful for:
Play your GC imports
Copy your copy-protected saves to SD easily
Move Disc Channel
Banana Patcher needs IOS36 with trucha bug and patched ES_Identify function, or a pre-3.4 version of it.
WARNING: Banana Patcher doesn't modify your NAND. However, it's still a dangerous application so use it at your own risk!