Yep, I'Sync Lite (sounds like a boy band, doesn't it?) came bundled with the T665.
It looks like the problem is that the Lite version of that program won't sync any information except for "Business Address", so people for whom I have only a home address lose the address info on the Clie.
I downloaded Chapura's KeyContacts last night, and it seems to have fixed the problem by allowing data to sync from fields other than "Business Address". It's a pretty slick program, even allowing multiple categories for contacts (i.e., Business and Personal for friends I work with). It's a touch pricey, for a datebook utility, though.