Good topic, Declan!
Ken Evoy would certainly top my list, too - I've been reading his material, and involved with the 5P, for several years now. But currently - I would have to say the most recent positive influence on my business has been Joe Vitale. I find that what I've learned from his material is affecting every aspect of my business - right down to how I write my meta tags, of all things. I had never taken much of an interest in copywriting before... but it has really changed the way I
think. His Hypnotic Copywriting Manual was probably the best thing I've sat down and read all year.
I cant go without mentioning Perry Marshall, though. I love his style, and he has the most in-depth information on PPC & increasing conversions that I've ever read. Not necessarily focused on affiliate marketing, but on promoting your own website & products - very good stuff. What I've learned from him this year, through his book and various interviews, has
really helped me to increase my profit with pay-per-click advertising!
Gosh, there are so many more names I could mention... People who have had an influence on me, tips & gems I've picked up along the way - friends and peers who have encouraged me... I could write on this topic all day, I bet!