Easiest way to get banned from this site is comparing it in any way to ninja250.org. Kidding. Mostly.
That site is a kludge of custom code built over 10 years into the steaming morass that it currently is. I'm glad they were able to integrate a geo-searching algorithm into their profile search, but until there is a plug-n-play vbulletin module, it's unlikely that I'll be able to implement one on ninjette.org for the foreseeable future. I've found a number of Ruby on Rails as well as .php only modules that accomplish that, but it would require hooking into our vbulletin member database in a way that I wouldn't feel comfortable with.
If anyone happens to find any other vbulletin-based site that has zip code proximity searching enabled, point me to it and I'll see if I can get hints and tips from the creator of that site.