Download my Biology Education Software FAQ from
ftp.zoology.washington.edu /pub/doc/ (new release tonight) or look
for it on the web at a number of sites including
http://www-hpcc.astro.washington.edu/scied/bio.html
In there I describe several programs which might be useful to you.
Among them are the programs in the BioQUEST series, which include
several lab simulations relating to microbiology, a couple good
genetics lab simulations (Virtual Genetics Laboratory and Virtual
Flylab), and some other stuff.
Good luck,
Eli Meir
Dept of Zoology, Univ of Washington
meir at zoology.washington.edu