Other useful sites you might want to look at.

Six Minutes: Speaking and Presentation Skills

Always has high quality articles and is updated frequently. This is my bread and butter for public speaking research on the web. I encourage you to take a look.

Public Speaking Tips

The site hasn’t been updated in a while, but I suggest you check out the 165 articles they already have. I used to read it religiously and they have some pretty insightful stuff.

Professionally Speaking

There are tons of audio interviews with professional public speakers. Really top notch blog.

Speech Mastery

The sheer amount of great articles on here is incredible. I can really only scratch at the surface when I peruse here. They have articles on not just public speaking, but interpersonal and job interview skills as well.