Brandon Wu made this product
I used to keep track of people on a spreadsheet but the list got too big to manage (also I needed visual reference for designers/artists). So I asked a friend to help me build a simple tool to replace it, and it became markd.co. It's a simple browser button for you to save people with tags/notes/images, and a minimal web app to manage your contacts.
It's free - feel free to give it a spin! :-)