Here are some wonderful sites on the web that help with presentation, even if they don't directly concern the art of magic:

Dramatica.com

Essential Magic Conference videos

Heath Brothers Blog - Chip and Dan Heath are the authors of the book Made To Stick. To see how this relates to magic, check out my blog posts on the principles from Made To Stick:

Memorable Magic: Simplicity
Memorable Magic: The Unexpected
Memorable Magic: Concreteness
Memorable Magic: Credibility
Memorable Magic: Emotions
Memorable Magic: Stories
Memorable Magic: Wrap-Up

Jim Hull's Story Fanatic Blog


Below are some resources that haven't been updated in quite some time, yet still provide valuable advice:

Creating Passionate Users Blog

Stage Stuff by Richard Tenace