BlockWild is a Google Maps mashup that allows users to post, search and discover location-based, community-generated content like events, social groups, classified ads, jobs, real estate and Yelp reviews.
The site is a great way to see what is going on around you. The site geo-locates and relies on user-generated content so at the moment some areas may have more content than others. San Francisco and New York already have a lot of content and other areas will become more useful as people add content to the map.
You can browse the map by clicking on the color-categorized map markers or use the search box. The custom designed information windows are very cool, with tabs for information about the listing and for tags. The information windows have been designed with JQuery and look a lot more attractive than the default Google Maps API windows.