Map and search real estate listings with google maps

I currently have a simple application that maps real estate listings with google maps and maps nearby listings. I would like to add a feature that would allow someone to drag a bounds box on a google map and view listings within that box. I would also like the ability to do a search to narrow down the listings displayed to those that meet certain critera which the user could choose. All listings are containted in a mysql database and have geo location lat and lng in place. No need to geocode addresses. I have a link to a site using a wordpress plugin that is doing this same thing if someone would like to see it in action. However my site is not wordpress so am unable to use this plugin. I am open to othere mapping sources, it does not have to be google maps. I am looking to either add on to what I have or it may be easier if you have done this before to use your entire mapping application.