What's that guy at the coffee shop typing into his computer? These days you may actually be able to find out. If he's using Twitter or FourSquare, nearby messages can be called up using the APIs. The new Geosay mashup does exactly this, showing tweets and tips near your location--or any location you request.
Geosay has a number of ways to discover locations. It uses the W3C standard to attempt to find you, which works in many browsers (including mobile). Then it falls back upon IP geolocation with Maxmind (our Maxmind API profile). You can type in an address or landmark and it queries Google's geocoder. Finally, you can just drag the map to the desired search location and click the link at the footer of the map.
According to its creator, the project took a weekend. It's really a slick interface that does a good job of integrating the two data sources. Geosay even looks good on iPhone and iPad, forgoing the map but still doing a good job of getting the content to you.