I have always done first and last names, even on my iChat and AIM contact lists.
I use a Blackberry so I obviously have more options for my contacts. I don't have many pictures yet but I"m working on it. But not only do I have their last names, but I usually have their cell #, work #, and home #, along with their job, job title, and where they live, and some have their corresponding email addresses as well. This is for friends and business contacts.
When I meet new people, I just start off with their cell number and their first and last name, as well as a nick-name. Once they get upgraded to "friend" then I will ask for the rest of the info.