BEN is a digital library portal for teaching and learning in the biological sciences. There is a vast collection of resources which can be browsed by subject, type of resource, or grade level.
There is a K-12 educators page that also contains some information on teaching strategies. Teachers can submit resources as well.
Applications for Science Teachers: K-12 teachers of life science will find a large and flexible database of resources. While there are elementary and middle school resources, most of the support is in the high school and college range. Definitely worth adding to your bookmarks.