Infoplease.com is an encyclopedic site for geography that also includes almanacs, atlases, natural features and timelines.

I enjoy learning about agriculture and so for me, the usda.gov site is beneficial because it has lots of information on agriculture, food and nutrition and rural and community development.

Local.live.com is a really interesting site because you can take virtual tours of cities with different buildings and landmarks--it's almost like you were there.