I have also found that it is extremely helpful to have many detailed categories for classifying people as a kind of reminder. I work in development, and the number of people I have in contacts is large and diverse.
I have categories for type of work, or for their type of interest and mission (gender issues, birdwatchers - whatever) and even for functions (Reunion, Denver workshop, etc.)
I keep multiple catgories in Outlook. [Briank, I may look into the idea of keywords in notes instead- that might get around the category limit of my handheld.]
It is especially helpful to have extensive categories when I am trying to place "now how do I know Jane?" and surprising (and face-saving) to realize from a quick look at contact categories that I must have run into her at least three times this past year at various functions.
Sounds like a good system to me!