Learn Genetics is a great resources from the University of Utah.
Learn Genetics has interactive videos and demos that explain different concepts of genetics. The web site is nicely designed and easy to navigate. There are articles about genetics and the technology behind it, virtual labs and much more. The virtual labs include DNA Extraction, PCR, Gel Electrophoresis, and DNA Microarray. Most schools can't afford the equipment and supplies to do these labs for real, so this site is a great alternative and the students still learn about the concepts.
There is also another site from the university called Teach Genetics which is a beta preview teacher companion site for Learn Genetics. There are some resources now, with more coming in the future.
These are great resources for Biology and Genetics teachers.
My wife, a Biology teacher, found them and told me about them. She found them very useful and easy to use. Her students loved the virtual labs and learned the material while experiencing something new and fun.