Joan Stewart of The Publicity Hound. Joan offers dozens of free articles on her site in relation to enhancing your public relations effectiveness. I've only included a couple here that relate specifically to photography but Joan is a great resource and I recommend you check out her site www.publicityhound.com
David Meerman Scott is a best selling author of "The New Rules of Marketing and PR" and "World Wide Rave". David also offers alot of free content on his site under the Resources page. If your interested in Social Media check out David's site at www.davidmeermanscott.com
Donna Templeton is Marketing Director for Andy Templeton Photography and has over 15 years B-to-B marketing experience. Donna has run several marketing departments with million dollar budgets and her background is complemented with a BA in Marketing, MBA and Master's Certificate in Internet Marketing.