Virtual Classrooms, Games, and Simulations

I have been exploring the benefits of virtual classrooms, games, and simulations in a learning technologies graduate class. Anyone have experience with these technologies at the high school level? 

I teach high school chemistry and have used a virtual chemistry lab for 2-3 experiments per year for the last four years.  There are set labs that students can work on from a lab manual or they can experiment freely in a either an organic or inorganic lab with access to a stock room.  It's a neat application and very interactive to the point that it let's students "smell" when they're making observations, something that would be missing from a virtual experience. 

What are your thoughts on virtual dissections?  Any biology teachers out there using them successfully?