I just visited Pleasant Hill Rambles. J mentioned a couple of gardeners who are organizing systems to keep track of their plants.
I also began an organizational project very early this Spring. Right now, it's a in pocket-sized notebook... a spiral bound set of 50 3x5" index cards (bound on top) that flip. The back side of each card is blank, useful for drawing and mapping. The front of the next side is lined, useful for recording. (You can click on these photos to get a better view and idea of how my system works.)
Hopefully these photographs are good enough to give you an idea of what I've done. The back of the cover and the front page hold a "table of contents." You can see that some of my pages didn't have enough room for all the listings. They've had to spill onto other pages. Oh, well.
Someday I would like to take these maps and information and transfer them into a pocket notebook that will hold the original markers that came with the plants. I also anticipate noting when I planted each one (if I can remember!), special care notations, etc.
But, for now, this is dandy. And very easily carried and added to. :-)
*In the gardens, I have plant ID markers by nearly everything I've planted... at least nearly all the items I've purchased since we moved here!
Sometimes being "Shady" is just not enough! ;-)