I have to confess that, until today, I was still converting latitude and longitude by Googling "convert GPS coordinates" and putting it into whatever came up first. That just changed when I found Tiny Geo-coder. It converts coordinate pairs to addresses, and vice versa. Not only that, but it has an API, so you can use it in other web projects that require coordinates.

One of the first real-world uses of Tiny Geo-coder can be seen on travel.perfectspace.com, where the authors are passing their check-ins on Brightkite through Tiny Geo-coder to generate a map of their location for display on the site. Another possibility that comes immediately to mind is converting the coordinates that the iPhone version Twitterrific generates into the name of the location for your Twitter profile. I'm sure clever people will come up with some even better ideas for this little app.