Apologies if you've already got these in comments (are you updating the original list?) but:

Australian Google fool (http://www.google.com.au/intl/en/gday/index.html)
Various news stories linked from the Telegraph's roundup (http://www.telegraph.co.uk/news/main.jhtml?xml=/news/2008/04/01/napril201.xml)
web standards (http://www.webstandards.org/2008/04/01/new-initiative-in-hyper-localized-social-tagging/)
Local April Fool by me and rejs :-) (http://www.oucs.ox.ac.uk/network/f2f.xml)