The Easter Eggs are discussed somewhere in the forum, but you can also read about them at:
http://www.geocities. com/kristopherwindsor/bike/eggs.html
These are the easiest to enter through the graffiti, and I am not sure how to do them on a hi-res+ Palm.
If you already have on-screen Graffiti enabled, you can skip the Toggle Full Screen thing and just input directly on the screen similar to in the Graffiti area.