BirdForum is a great resource for discussing anything to with birds and birdwatching, with thousands of users from around the world. The identification Q&A is particularly useful if you get a picture of a bird you can't identify, with users usually clamouring to ID it for you!
The site also has a Wiki that all users can edit, which looks set to become one of the greatest databases of bird species and bird-related topics anywhere on the Internet.
The forum has a section of birdwatching blogs by its users. Some of the best, and most regularly updated, from UK birders include:
Tales of a Botanical Birder
Colin's Birding Diary
Birding by the Criminally Stupid