I just upgraded my phone, and I’m in the process of transferring all my stored numbers from the old handset to the new one, via the wonders of Bluetooth.
Because this is a fairly laborious process, I don’t want to transfer any numbers over which I don’t think are valid, or haven’t used for a long while, or think I won’t use again. This activity, which I complete every time I change phones - so, once a year or thereabouts - , causes a pruning effect among my contacts, by making me re-evaluate the viability of social and business contacts, which feels a little clinical, but has to be done, nevertheless.
So this year, I’m waving goodbye to a bunch of people who I haven’t been in touch with for ages (mostly business contacts, but some social acquaintences who I think must have moved number by now). My rationale is that if I ever need or want to get in touch with them again, there’ll be a better method to do it than randomly calling out of the blue, and these days I can be fairly confident that people are trackable-down (down-trackable?) via mutual contacts, t’internet and so on.
There are exceptions, of course. There are some names and contacts in particular (mostly social, but some business, too) which I hold on to, despite not having used their numbers for years, or been in touch with the contactee for as long. There’s something about not wanting to throw away the tiny bit of potential contact I have with someone, or in most cases, despite the number being (probably) obsolete, I don’t want to delete the idea of the person from my life. I want to be reminded of them, so that I am reminded to track them down if I do want to get back in touch with them at some point.
This goes beyond reason, and I know how silly it seems. But I bet other people do it, too…
I’m also reminded during this annual ritual, as ever, about how marvellous it would be if I could import the dictionary of all the words I’d taught my old phone, so that I don’t have to go through the process of teaching my new one all over again. I also think that such a word list would be fairly revealing about me, and my social communications….
Any ideas if/how this can be done these days?

Trackdownable?
Does your phone work with FMA? http://fma.sourceforge.net/
It’s the best s/w I know for connecting mobile phones.
You’ve still got the iMac, right? Depending on what model of phone you have, syncing vcards through Address Book varies from “doable but tiring” to “doable in an instant”. Sony Ericsson support is by far and away the best; Samsung is at the bottom.
If it’ll work with iSync, though, you’re in. But you can still send vcards by hand without iSync through Address Book. That might be worth trying; it’s how I keep everything up to date (although this shitty Samsung phone I’m about to get rid of has never made things easy).
I was going to say basically the same thing as Tom; when it works well, iSync and your address book can be pretty handy.
I change my phone probably once every one or two months, so this has become second nature to me. Sony Ericsson definitely works best (I use a K800i at the moment and it took maybe ten or twenty seconds to sync about 500 contacts) but it pays to check out the situation before you upgrade (or download the right drivers to your Mac from some lovely person on the web). Also, if you group your contacts properly, you can use it just to sync the ones you need, whlie leaving the others on your desktop for whenever you might need them.
Dunno about the T9 dictionary, though. It never quite seems that mine EVER learns the right words. It would be lovely to be able to sync that stuff up too, but then not everyone uses T9.
Yeah - the nice thing with iSync/address book is that you can get it to only sync people with phonenumbers, so you don’t get a phone full of email addresses.
iSync is a more fiddly beast than the plain-old Bluetooth button in the Address Book, though.
I keep memory numbers Meg, you are not alone. I also keep a text diary which is much worse and much more work (I refuse to modernise it and handwrite them all out - it is beautiful)