The writing site of them all is probably the misc.writing newsgroup site. misc.writing is, after all, the writing newsgroup, the biggest and the best.
Readers of Writers News and Writing Magazine will be familiar with Kye Valongo's articles on writing and the Internet. Kye has a good, informative writing site at UKwriters
Another uk Internet Writing Resource is wordup
The lottery-funded Opening Line is a group of writing courses (now all full) run at various places in Yorkshire. Their web site started off as a showcase for Opening Line members, but has expanded to become a very valuable resource offering lots of information, links, and the chance for writers to have samples on-line or links to their websites