image from www.csc.edu/images/
There are lot's of great resources for Biology out there:
Great collection of movies about cell biology that you can use to illustrate concepts and topics.
Biologic Photography - great microscopic pictures of plants and animals. Great for getting students engaged and excited about a topic.
Anatomy Wiki - a great resource for learning anatomy. The site encourages students to contribute content also. There are discussions, videos, photos, and case studies.
Polar Bears International - Polar Bears International is a group that focuses entirely on Polar Bears - their habitat, behavior, and survival. There are some great educational resources on the site including lesson plans, posters, videos, links, PowerPoint presentations, and much more.
And some previous posts with Biology resources: