Well, it's hard to recommend anything specific without knowing your knowledge level and specific needs, but you might find something if you search `<language> tutorial` or `<library> tutorial` or something like that on YouTube. There's also Show Me Do, which is a place dedicated to video tutorials. I'd personally recommend learning Python if you're just getting started, and then C++. After that, it all really depends on what exactly you're planning to do. Python is just fine for scripting, though shell script would be nice to learn for that; C++ is pretty much all you'd need for ports; and for original programs, just about any language that works on the Pandora will do.
The only thing to keep in mind for the Pandora is the controls, and OpenGL (which needs to be converted to GL ES). Other than that, coding on the Pandora is just about identical to coding on any other GNU/Linux PC.