Just in case the plethora of crossword magazines out there isn't enough for you — "More, more!" I hear you cry! — there are vast numbers of online crossword sites.
The Guardian website has a huge collection of cryptic and quick crosswords, from over 30 setters. They have an archive crossword search function, so you can easily locate puzzles by your favourite setter, type, or publication date. You can also sign up for the crossword editor’s monthly update email, and participate in discussions about each crossword in comments below each crossword. You can either solve them online, or download print versions to do with pencil on paper.
The Puzzle Wizard series of magazines is produced by the excellent independent Australian puzzle writer and publisher, Greg Parker. His website includes a bunch of puzzles to solve online. There are six crossword themes you can choose from Straight Crosswords, Movies, AFL, Cricket, Music, and Television. There are also 100 free crosswords. They require a Java plug-in to work, which can be downloaded here, if you don't have it already.
If you really want to test your mettle, then The Times is the place to go. This is a subscription service, via their Crossword Club, and includes the famous (infamous?) Times Cryptic, as well as quick crosswords, codewords, sudoku, and bridge and chess problems.
The Mirror Online is a UK site, with a whole lot of free crosswords. The cryptic is of an easy level, and there are also quick and quiz crosswords to try.
If you like rude cryptics (and who doesn't?), then The Private Eye cryptic crossword is for you! This is a very UK-centric cryptic, with plenty of politicians' names etc, you have been warned. My goodness it's rude. This is the link everyone's going to click on, isn't it.
The Clue Detective Puzzle Agency is an Australian subscription site, with an annual membership fee. There is a huge collection of online puzzles, which can also be printed, or solved on iPads etc. They include trivia quizzes, codewords, regular crosswords, general knowledge crosswords, crosswords for kids, and cryptics (my Nixie ones, only place you can find 'em).
And if that's not enough for you — "More, more!" I hear you cry! — Crossword Puzzles has a good (although not exhaustive) collection of links to even more crossword sites and resources.
Now, you can never complain about not having enough puzzles to solve! So there.