[iBook] what contact management software?

[ibooklist at matthurst.fastmail.fm]

Does anyone have any recommendations for cheap/free contact management.
I'm freelance and I'm planning a marketing push - a ringround, with
email and mail out followup, so it doesn't need to be major. I could do
something with spreadsheets, (I don't have MS Office), but I was
wondering if there were any cool solutions out there.... not even
Mac-reliant, necessarily.

Matt

PS the wifi problems I had earlier have 'healed' now. I suspect it was
the OS X update too.