Canine Body Language: A Photographic Guide: Interpreting the Native Language of the Domestic Dog by Brenda Aloff
[I want this too! 
]
On Talking Terms with Dogs: Calming Signals by Turid Rugaas
[and this one]
Click to Calm: Healing the Aggressive Dog (Karen Pryor Clicker Book) by Emma Parsons
[I have this one and it is pretty good, as the principles can be applied to calming any dog, not just those that are aggressive - however, for some reason I just couldnt get into it like I have some books]
Understanding and Handling Dog Aggression by Barbara Sykes
[hhhmmm, I wasnt convinced by this one - might be one to borrow from the library and see what you think?]
Mine!: A Practical Guide to Resource Guarding in Dogs by Jean Donaldson
[yes I have this and it is very good - but it is almost like a course booklet to advise a beahviourist on how to put a programme together to help a dog/client - or perhaps when teaching students - excellent all the same though]
Oh Behave!: Dogs from Pavlov to Premack to Pinker by Jean Donaldson
[this was a fun little read - one you can dip in and out of - quite humerous in parts - almost like a little collection of stories but instead it is about different training theories principles - not much info on each though]
Control Unleashed by Leslie McDevitt
[absolutely EXCELLENT - this has to be my absolute favourite book of last year - and i have a fair few! 
- i did a little review of this in another thread so will try and find it for you]
Edit: ok cant find the old post so just a quick summary on Control Unleashed:
It was originally developed to help dogs to be calm in the performance dog sport environment (like agility or flyball etc) but I have found this to be so useful just in general - I only wish I had got it earlier! and an absolute must with any form or reactive dog, whether that be aggression, excitable, fear etc...(maggie was very excitable and it has helped me - and her - loads).
It is slightly wordy and I would suggest taking the time to read the first couple of chapters to set the context, but after that you can kind of dip in and out of the chapters. The nice thing is that the methods are structured like games -this is what i love so much about it. everything is fun and although you can be dealing with quite serious issues, everything is sitll a game for you and the dog...and they are all aimed at teaching self-control. I love the 'Look at That! game - it is brill.