Social navigation

Waze is a social mobile application providing free turn-by-turn navigation based on the live conditions of the road. 100% powered by users, the more you drive, the better it gets. Join the community of drivers in your area today!

citeulike is a free service for managing and discovering scholarly references

Keep, share, and discover the best of the Web using Delicious, the world's leading social bookmarking service.

Diigo is a powerful research tool and a knowledge-sharing community.

Google Reader helps you find and keep track of interesting stuff on the web. You can subscribe to your favorite websites, see what your friends are sharing, and keep up with what's popular. New content comes to your Google Reader when it's posted, so you don't need to visit individual sites.

Plus, Reader keeps track of which items you've read, so you only see unread items when you come back. If there's a dark blue border around an item, Reader is marking that item as read.

StumbleUpon is a discovery engine that finds the best of the web, recommended just for you.

folkd.com - Social Search and Bookmarking - Save your link online and search what your friends like.