There are a number of interactive and multimedia sites on the web that are useful for educational purposes, but aren't exactly "slick" looking--like those done by professional web masters. This site on cell biology is like that: http://www.johnkyrk.com/index.html
This site contains a number of animations designed to explain various aspects of cell biology. The topics include: cell membranes, glycolysis, Golgi apparatus, Mitochondria/electron transport (to name a few).
This site is much slicker than the one listed above:http://learn.genetics.utah.edu/content/begin/cells/ Click on "Inside a cell" and you'll be taken to the outside of a cell. Mouse over the cell, and you'll get a look inside. Click on an organ, and you'll get a slick video, complete with sound effects describing the organ and what it does.