can anyone recommend any good books on dog aggression?  Ive seen a couple on amazon, but it would be nice to know if any of them are actually worth buying.

James O'Heare is the best one to read IMO.

hi do u have a link to a site where i can purchase this book?

Click to Calm (Healing the Aggressive Dog) - Emma Parsons.  Available on-line from Crosskeys Bookshop amongst other places, they'll probably have the James O'Heare one too.  Or Jean Donaldson "Fight!"  Assuming you meant dog to dog aggression.