Excellence and total access!
www.accessexcellence.com
Access Excellence is every biology teacher's dream. It has past lesson plans by topic; archives go back quite a few years. I especially like the graphics gallery which has illustrations for just about every biological concept (see above). They have the latest news in science and activities (another word for short, hands on labs/demos you can do with classes). http://www.accessexcellence.com/AE/mspot/ is the Mystery Spot which has higher level thinking (upper level cognitive and application type) activities.
I have used this site more often as a resource for diagrams (for overheads and powerpoints), activities as ideas for extended labs. Check it out, you will be impressed.