International Institute for Geo-Information Science and Earth Observation (ITC) Remote Sensing Information
This site offers links to hundreds of sites related to remote sensing. It is a great resource when looking for remote sensing information.

Earth Observatory
This is an excellent NASA-sponsored site that publishes easy to read examples of how satellite data are used for a broad variety of applications. There is also a great image archive illustrating several Earth Science concepts. They have an "image of the day" that often depicts some significant natural or anthropogenic event happening around the world.

GISUser.com
A GIS-focused site with access to a lot of useful resources. They sponsor an electronic newsletter that is delivered 3 times a week providing news updates and feature content focused on GIS, geospatial technologies and remote sensing. Subscription information is free and can be done by visiting the web site.

SlashGISRS
This is a nice user-driven web site to read about and participate in discussions about GIS and remote sensing happenings.