Richard Byrne writes a fabulous blog, Free Technology for Teachers. In his regular newsletters, he reviews apps, classroom web tools, and loads of wonderful resources for students and teachers alike. His manuals on how to work with Google resources, as well as how to create videos, blogs, and websites are must reads. Sign up to receive his newsletter today!
Another great source for resources on using technology in the classroom is Digital Classroom at TeachingHistory.org, the National History Education Clearinghouse run by the US Department of Education.
Edutopia has many topics devoted to technology and education. Check out their guide to using web 2.0 tools for lesson planning as an example of what they offer.
Most major technology companies offer special resources for teachers. These vary from online tools to use their products in the classroom, to connecting teachers to share lesson plans and curriculum resources. Here is just a sampling: