This is a very structured interactive animation about PCR. It has an associated background essay, and some discussion questions. The thing I like about it is that it is an application of transcription.
From the site:
"In this interactive activity adapted from the University of Nebraska's Library of Crop Technologies, learn the basic steps of polymerase chain reaction (PCR), a technique used to produce short sections of DNA for analysis. In this technique, various components are combined in a microfuge tube and heated in a thermal cycler. The activity details the process, which results in thousands of identical copies of a DNA fragment. Note: The activity provides a simulation of the process. The characterizations of depicted components and their behaviors should not be taken literally."
this was one of the biology databases i originally found that I thought would help teach biology in an interactive way. It has resources for many subjects, but there is a biology one in particular. One tool I found interesting was the podtutor. "PodTutor includes audio study tracks, diagrams, and detailed text notes, which can be instantly Podcast to your pc, or mac, using iTunes, and stored on any mp3 player, putting the subject knowledge of senior examiners, experienced teachers and tutors in your pocket."