FWIW, I also use my Palm - previous an m505, and now a Tungsten T - for all things GTD. I based my setup off of the tips found here on the website.
Admittedly though, I use Agendus as my schedule/calendar program, and I keep a few of my less used reference lists in Bonsai. The bulk of my data is in the todo application; with supporting data, inspirations, open/hours, and misc other things being in the Memo app.
I don't use the "power" features of Agendus (colors/icons/etc.), but I do use the contact linking because it helps keep things organized on the Desktop (GoldMine). I also just like the look of Agendus - especially the beta I've been playing with in the past few weeks.