http://www.amazon.co.uk
I often buy from Amazon. Books arrive within the stated time and prices are very competitive. Look out for the offers on free postage.

http://www.barterbooks.co.uk
A visit to the bookshop in Alnwick, Northumberland, is a very special experience. There are treats in store for on-line visitors too.

http://www.bartleby.com
Whether or not you want to buy, here is a treasury of poetry and fiction. Also an excellent site for on-line reference books.

http://www.haybooks.com
No time to visit the tea-shops and second-hand bookshops in Hay-on-Wye? Well, this site, has a database of over a million books relating to stock in all the bookshops which you would have visited, so put on the kettle and start browsing.

http://www.sportsbooksdirect.co.uk
Began life as Sportspages, a specialist book shop in Manchester and London, but now does business via the web worldwide. Still the best place to find last season's college football rushing statistics.

http://www.thebookpeople.co.uk
Cast your eye over this sight from time to time. Excellent bargains to be had.

And finally, for all sorts of books about Derbyshire pay a visit to Scarthin Books at Cromford.