Poins' Crosswords      

http://en.wikipedia.org/wiki/Cryptic_crossword

 This site provides a fund of information about cryptic crosswords.

 It includes a particularly good section on the different types of cryptic clue.

http://www.onelook.com/

  Definitions are available from a wide selection of online dictionaries.

http://www.bestcrosswords.com/bestcrosswords/guestconstructor/GuestConstructorProfile.external?sp=S11

   This site offers both British and American ‘quick’ crosswords. Poins supplies this site with puzzles under the name of Ron Major.

Excellent software for compiling crosswords

A clue writing competition and a monthly prize crossword are
amongst the many interesting features to be found at Derek Harrison's
crossword resource centre.

Aplus.Net Web Directory

 An online business directory

Fifteensquared

A site offering blogs on crosswords from several publications
including the Guardian and the Independent.

About.com

A selection of cryptic crosswords chosen by Dave Fisher

Best For Puzzles

Michael Curl's site offers daily cryptic and quick crosswords and plenty to interest crossword enthusiasts.

Thinks.com

A family-oriented games, puzzles and pastimes site.

E.J's Crossword Showcase

Lots of cryptic and straight crosswords from one of the UK's leading setters.