nearest addresses

I purchased Pro Maps Google and have installed it.
It's a nice extension however, It falls a little short of what I'm trying to achieve.
I was wondering if Web Assist has a solution recipe or could assist me with the following:

When visiting my clients site, the visitor is going to enter their Zip Code (could be City or full address. But I'm trying to keep it simple)
After clicking Search, any addresses close to the entered Zip Code will appear on the page.
Clicking on each location, will display the Google Map.

I thought the Google Extension tool could help me accomplish this. I went through all the solution recipes. I could not find anything that would help accomplish displaying nearest addresses to the one the visitor enters.

Thank you for your help,
Danielle