... draw yourself up to 6 memos that get stored to your CF card via the hacked GBA MP. The only problem I have with it is that it saves the memo files to the root directory, which I try to keep clean since I'm using MightyMax's Multiloader and a folder structure to keep my files organized. But still, this just brings us one step closer to the DS as PDA. The biggest complaint I have is that the touch screen support suffers from that old problem where it occassionally jumps across the screen.
Source code is available (which should help me in making my own app but with a virtual keyboard and text, as well as maybe I can change where it saves and reads the memo files from).
*(note: the first time you run it, it takes a bit before it responds, because it's saving files for the 6 memo saves, so sit tight for a minute)
... back-up and restore NDS game saves to your CF card via the hacked GBA MP. It also supports back-up and restore from SRAM. Though, I haven't been able to get it to work. The NDS EPROM TOOL worked, but doesn't seem to support Type 3 saves, like in Advance Wars or Nintendogs. RAIN supports those, but all I get is a white screen. :/