Here are just a FEW websites available to teachers to provide information on distance learning:

Global Virtual Classroom - A site for teachers to sign up their class to work with other classrooms around the world to create a website.
Awesome Highlighter- A tool students can use to highlight information on websites and save the site to refer back to.

Wikispaces- A place for people to connect, post and interact all in one space.
Ways to use Wiki
Coffeechug- An example of how a teacher uses a wikispace to connect his classroom to other classes all over the globe.

Geocaching- A site that connects geography and people around the world by seeking small treasures and logging results.

Virtual Field Trips

Realistic Field Trip
Virtual Virtual Field Trip