If you’ve used services like foursquare that let you check-in to a location or leave tips, then you’re familiar with the concept of leaving your digital mark on top of a geographic location.

The service SkyChalk doesn’t want you to check-in though, it just wants to know what you have to say about a certain area, no matter where you are.

With a great spin on the Google Maps API, SkyChalk lets you annotate any location on a map, even if it’s not a location to check-in at, such as a restaurant.

For example, you could use SkyChalk to write a note about that chance encounter you had with someone, hoping they’d one day find the service and read it.

Chalking the globe

The different types of use cases for SkyChalk are limitless. When you sign up for the service, the app picks your current location and shows you all of the notes people have written about different areas around you. People can submit notes with their names, or anonymously if they choose.

SkyChalk 1 520x299 SkyChalk lets you leave notes on a map, anywhere in the world

With no need to download an app or check-in anywhere, you are free to surf around Google Maps for locations that bring back memories to you. The service is also extremely useful for policing a community, as you can point out tricky sidewalks or faulty traffic lights.

All of your notes are tracked with your profile, so if you post them with your username, other users can check out all of the places you’ve annotated. It’s quite an interesting geographic based social network, with no bounds or rating systems for locales. You can however, vote up someone’s note as a sign of appreciation or usefulness.

One thing I’d like to see is the ability to make notes private, as this would be a great annotation tool for travel, without all of the social aspects.

If you travel a lot, or really care about the location around you, then you might want to give SkyChalk a try. I’ve found a lot of silly comments about how rude a waitress is, or how certain blocks in San Francisco are full of girls who aren’t single, so whether you’ll find it useful or not is up to you.