Links
devkitPro
This is required to use PAlib.

CPlusPlus.com
In order to use PAlib, you will need to know C or C++. This site is a convenient reference, though it mostly focuses on C++.

tilemap.co.uk
Homepage of Mappy, a powerful tilemap editor that can be used for the DS with a bit of effort.

Charas-Project
The original Charas-Project, THE online source for RPG sprites customized to your liking. Updated rather frequently and has an active forum.

nintendomax.com
A French site covering Nintendo homebrew news. Lots of links to other Nintendo sites as well, though mostly in French.