Here are some useful links. (More to come later)

General Sites About Dragonflies
British Dragonfly Society Essential Viewing
Atropos Magazine The only magazine to regularly feature dragonflies
Digital Dragonflies Scanning dragonflies - an alternative to photography
The British List Wikipedia article listing all British Species

Norfolk Sites
Norfolk & Norwich Naturalists' Society
Wymondham Nature Group
Norfolk Wildlife Trust
Norfolk Walks
Naturenet Norfolk
Norfolk BioDiversity

Other Useful Sites
The UK Phenology Network
Watkins and Doncaster
Royal Entomological Society
A listing of world dragonflies, currently incomplete
Flickr Dragonfly Photo Pool