I, too, use the large index cards for keeping all my addresses. The only ones I keep on my computer are the ones whom I write to regularly. I go through my Outlook address book periodically to delete names that I don't recognize, and addresses I don't have names for.
Not only do I keep much of the same info that Lucky mentioned (BTW, welcome, Lucky!) like name, address, phone, e-mail, kids' names, b-days, anniversaries, and death dates if applicable, I also keep a record of Christmas cards sent and received on the back.
That's my Master Box.

Ah, kindred souls! You ladies are great!
Kelly H.