I've taken the Dale Carnegie course, and am presently a Toastmasters member.
If you can afford the $1500 (or if your employer is willing to pay for it), Dale Carnegie is an excellent "boot camp" for speaking skills, as well as other leadership skills.
Toastmasters, is a good place not only to learn public speaking, albiet at a more relaxed pace. It is a great resource to take advantage of even if you've taken a more intensive course like Dale Carnegie's, as it allows you to keep in practice, by having a place to speak on a regular basis.
Some Toastmaster clubs, from time to time offer their own speech course called "Speechcraft", usually given by more experienced Toastmasters.