Onotate the World
Onotate the World lets you annotate the world on Google Maps. To annotate the world with onotate you need to Tweet @onotate to get some sticky notes or make your own. The onotate sticky notes come in three kinds, a smiley face, an unhappy face and a 'meh' face.
Once you have your sticky notes you can then start annotating the world. If you stick a note on an object you need to take a photo and post a geotagged tweet with a hashtag of #like, #meh or #dislike depending on the note. Your picture will then appear on the onotate Google Map.
Onotate the World is a beautifully designed map. Which isn't surprising as it is a side project of onotate.com, a website that will allow you to present, review & annotate web design mockups.