First of all, I'm not even sure if this is the best way to do it, but...
I have amassed a table of longitude and lattitude points for all zip codes in the US. What I want to be able to do is allow a user to choose a zip code, select a radius in Miles (5, 10, 20, 40, etc...) and the app will list all the users in that radius.
It obviously doesn't need to be incredibly accurate, but it's got to be close. I've been poking around looking for other ways to do this but I'm stumped, and I can't find a good example of using long/lat to do it.
If I could get something in C# that would work best. I'm not proficient at Java but I might be able to muddle through it if absolutely necessary.