DNA from the Beginning
http://vector.cshl.org/dnaftb/
Primer on the basics of DNA, genes and heredity, using: animation, image gallery, video interviews, biographies, and links.

Other introductory web pages:

'What is a gene?' - beginner's guide from New Internationalist http://www.oneworld.org/ni/issue293/simply.html

Simple explanation of what GE is from PSRAST http://home1.swipnet.se/~w-18472/whatisge.htm

Short history of biotech: neolithic to 1988 in half a web page! from Pat Radin's informative site on GE and cloning http://students.washington.edu/radin/history.htm

Genetic engineering for kids a website for kids (of any age!) courtesy of Tiki the penguin http://www.oneworld.org/penguin/genetics/home.html
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BUT for a radical questioning of some of the key assumptions about what 'genes' are and how they operate, see 'The Century of the Gene' by Evelyn Fox Keller    
Review (posted to ngin list yesterday) at:  http://www.salon.com/books/review/2000/12/19/keller/index.html