Wrote this reply at work last night and then just didn't click submit. Brilliant.

I use Address Book rather successfully for this purpose. I use Dumb Groups to manually keep track of people I had in a class or networking contacts. For those in the class groups, I put a note as to what their research work was as well as their general research interests. Then, I can say, "Who was it that worked on Romans 14?" and then hit them up with questions and for discussion and such. Then, I use the notes field to keep track of the metadata for the person: where we met, who I know them through (for networking), interests, kids'/spouse's birthdays, anything else that might be important to remember. Then, if you notice some keyword coming up a lot, such as skydiving to use your example, you might create a smart group for skydiving and then if you are planning a skydiving get together, you can contact everyone on the list rather easily. If you didn't know, you can also add more "people" to their list than just "Spouse" such as kids, partners, etc. I make it a point to try to obtain a picture of all my contacts inasmuch as it's possible to do so as well as birthday and anniversary. I have learned not to underestimate the importance of sending out a card to someone for a special occasion who wasn't expecting it. That's golden. Also, creating smart groups for different locations (zip codes, area codes, states) is helpful if your contact list is large. So, if you are on your way to Chicago, you can glance at your Illinois list and see who is in the area that you might have a chance to meet up with.

For family, friends, and such like that, I keep a smart group called "Needing Contact" or some such and make it contain friends and family (from my friends and family dumb groups) and have the criterion be "not updated in XX days" (adjust number to taste). Then, when I have made my obligatory contact, I edit some trivial bit (Notes is a good place) and then it disappears for the list until next time. This isn't entirely effective in the event that you actually have to change something in their card, it won't show up for longer than your desired interval. Usually, though, if you have to change something, you have had some contact with them. My change just consists of a string of periods at the top of the notes. I add a new one for each time I contact them. I prefer this to actually adding a record of it in the notes such as "Called on 3/17. Talked for 7 minutes". If you use Salling Clicker and can remember to have your computer connected to your phone each time, it will keep a nice record of your calls within Address Book. I think BluePhoneElite will do the same.

So, that's sort of how I am using my Address Book. It's a work ever in progress (isn't everything Beta these days?) but I hope this helps.