In my milieu, family names tend to be diverse and given names much less so. As social interaction becomes more informal, this is increasingly problematic. It is perfectly possible to see someone socially for years and know quite a bit about them--their birthplace, their romantic history, their likes and dislikes--and yet still not not know their surname. What strategies do you all use when you find yourself in this situation? Here are a few of mine:
1. Associated place: Could be city/state of origin, place of work or residence, or even just someplace they visit/talk about often. (For instance, we just nicknamed someone "Japanese Andrew" because he lived there before and speaks the language.) Around here we even use the names of high-rise apartment buildings, e.g. "Malibu East Dave".
2. Associated person: Generally a romantic pairing, e.g. "Gwyn's [husband] David". It's interesting how this can make two generic names suddenly specific, e.g. "Jim of Jim and Dave". (You may know lots of Jims and lots of Daves but only one couple comes to mind for "Jim and Dave".)
3. Associated quality: Historically, this was probably the most common method, but people I know don't use it much any more (perhaps the qualities are disproportionately negative ones and people have grown more sensitive). We knew one couple we called "the Two Jims" which we distinguished as "Young Jim" and "Old Jim".
4. Profession: Again, once more frequent than it is now. In an academic context, could even be a field of study, e.g. "Religious Studies Cate".
My spouse doesn't have a particularly good memory for people he's met only a few times so sometimes I find myself just spewing associations in the hopes a bell will ring, e.g. "You know, Tony. Bus driver? Goatee? From Indiana? Used to be roommates with Tommy?"