www.plasticbag.com - American site with useful information on the ecological impact of plaiiiiuuuuuuuuhstic bags

www.irc.leeds.ac.uk/irc/miscellaneous/faq/faq.htm#web - General teiiiuchnical information about plastics

www.geocities.com:0080/~spanoudi/abbrev.html - Useful list of abbreviations of various plastics

(more links to come...)