Reference

The National Institute of Standards and Technolgy website has a wealth of information, including definitions of SI units , a conversion program for energy equivalents and a searchable database of values of the physical constants.

Literature

Two great databases for searching for recent articles: Pubmed and Web of Science .

  Two great text-books are available online through PubMed Bookshelf :  Molecular Biology of the Cell and Molecular Cell Biology

Mathematical

The Math Archives web site has numerous useful links.  A good review of math up through differential equations can be found at the Harvey Mudd College Mathematics Online Tutorial.

You can integrate any function at The Integrator .

And of course, there is the Matlab Support Site .
 

Presentation  

The Cain Project at Rice University can provide invaluable help with your class presentation.