This resource has been around for awhile- but if you are a teacher of science you simply must visit The Complete Work of Charles Darwin Online and add it to your bookmarks. The site contains:
- complete collection of Darwin’s publications
- over 87,000 pages of searchable text & 207,000 electronic images
- at least one example of all of Darwin’s publications
- multiple translations
- private papers of Charles Darwin
Applications for Science Teachers: A great resource for teachers of life sciences this resource provides support for all learners of evolution and Nature of Science concepts. The scientific drawings and field notebooks provide rich examples for students.
Science for All 
Darwin online is a great site as is the Darwin Correspondence Project.
If you teach 11-19 year olds you might also be interested in these two sites created for Darwin year by the team at the Wellcome Trust, UK.
http://www.survivalrivals.org – practical experiments relating to Evolution
http://www.wellcometreeoflife.org – 5 minute video showing how animal life evolved – narrated by Sir David Attenborough
Hope that’s useful!
Amy