This week at agility training, my instructor said she felt my dog would benefit greatly from clicker training.  I'm interested in giving this ago and was wondering if anyone could recommend a good book?

Karen Pryor does a basic starting book that is really good.  Cant remember its name off hand but I am sure Crosskeys Books on the internet would have it.

Some great reading here (one of my favourite web sites)
You can dip in and cherry pick from great articles from some of the good and great in Clicker training..
Clicker solutions
HTH
:-D

Clickersolutions is an excellent site!
Also, I suggest "Clicker training for dogs" by Karen Pryor (think that's the one referred to above) and also if you really get into it, "Click for Joy" by Melissa Alexander, published by Karen Pryor's  "Sunshine books", which is just brilliant, and answers practically any question you could ever have on clicker training! :)

i have got a 4 month pup that i have trained using clickers,  i have also found training disks helpful to discourage those unwanted behaviours (worked wounders getting him to leave, really quick results) i find that he can be a bit unresponsive if he knows that you dont have the clicker and treats in your hand but when you do he can do anything..... he is still yound so when the behaviours are ingrained into his mind he is supposed to get weaned off the clicker and respond to praise and play.  its a great way to train and i have found that i hardly ever have to tell him off coz i just ask him to do something good e.g sit when he tries to jump on the sofa. good luck

Not a book, but I far prefer the I Click from Karen Pryor to a standard metal clicker.

"Clicker training" is an animal training method based on behavioral psychology that relies on marking desirable behavior and rewarding it. When an animal intentionally performs a behavior in order to bring about a desired consequence, as clicker trained animals do, they are learning in a way that researchers call "operant conditioning." The essential difference between clicker training and other reward-based training is that the animal is told exactly which behavior earned it a reward. This information is communicated with a distinct and unique sound, a click, which occurs at the same time as the desired behavior. The reward follows. A click is more powerful for training than a spoken word because it is not a sound heard by the animal in other circumstances. It means one thing only: a reward is coming because of what you did when you heard the click. It can be produced instantly and at the exact moment a behavior occurs. Even a very quick and subtle behavior, the twitch of an ear for example, can be clicked. The trainer clicks at the moment the behavior occurs: the horse raises its hoof, the trainer clicks simultaneously. The dog sits, the trainer clicks. Clicking is like taking a picture of the behavior the trainer wishes to reinforce. After "taking the picture," the trainer gives the animal something it likes, usually a small piece of food but sometimes play, petting, or other rewards. Clicker trainers differ from traditional trainers in that they wait until the behavior is well understood by the animal before using a command or "cue." A cue is the name of a behavior, such as "sit," or a hand movement or other clear signal. Until the animal knows what the behavior is, any name for it would be meaningless. Clicker trained animals want to perform behaviors for which they have been rewarded in the past. If they understand the meaning of the cue and desire the reward, they will perform the behavior. A consequence of any behavior can be unpleasant as well as pleasant. So why shouldn't punishments follow unwanted behaviors, just as rewards follow wanted behaviors? Clicker trainers allow unwanted behaviors to disappear through lack of reinforcement. If a behavior is not rewarding to the animal, eventually it will disappear. If an unwanted behavior persists, clicker trainers study the behavior to understand why it is reinforcing to the animal. Sometimes the behavior reinforces itself: a barking dog is less bored than a quiet dog. The barking is its own reward. The clicker trainer provides this dog with an alternate wanted behavior to replace the unwanted behavior. The bored dog may simply need more activity, or perhaps quiet resting for longer and longer periods can become a rewarded behavior. Then the clicker trainer would teach the dog a cue for "silence."

If you go onto the Learning About Dogs Site you will find clicker books aimed at various stages from the complete beginner through to experienced trainer including discipline specific manuals.  There are also DVDs and of course you can back these up by attending the various workshops etc that are on offer.

http://www.learningaboutdogs.com/acatalog/bookvid.html