Last week I noted that DB2 experts are essentially just DB2 pros who share what they know. Along those lines, if you're really interested in presenting on DB2 topics -- or if just want to muster the courage to talk in front of a room full of people -- you should check out Toastmasters International.
Years ago when I first started speaking, a friend suggested Toastmasters. I joined and got a lot out of it. The local monthly club meetings help you learn by doing. There are no instructors; instead you learn through the feedback of other members. You may be asked to give an impromptu speech about some topic just assigned, which teaches you how to think (and, of course, speak) on your feet. And you'll learn other speaking skills -- including timekeeping, grammar and parliamentary procedures.
The meetings are really low-pressure and fun. I remember a game where we counted the number of times a speaker said "um" or "ah." Most of the time you don't even realize how often you say these words. But the exercise and the feedback really helps here.
Even if you never go to a meeting, the Toastermasters site has some useful resources, including top 10 speaking tips and incorporating appropriate body language. You can also read the Toastmasters digital magazine, in particular this feature on incorporating humor into your speeches.
There's plenty more free material. See for yourself. I also encourage everyone to attend a local meeting.
If you have your own words of wisdom about speaking (like these), please leave a comment.