The fact that you have been invited to participate on panels is a sure sign that someone thinks you have a lot to say! You can jot down two or three points that you feel are important to share. You will also find that others will say things that stimulate pointers you have not planned to say. With regard to your stage fright and tension about speaking in front of others, please consider visiting my blog Speaking Freely at http://self-expression.com/speaking-freely for tons of new ideas on how to handle the tension of being the center of attention. One of the main discoveries I have made about stage fright is that those who have the most also have the potential to be among the most impactful speakers because they have their feelings up to the surface where they can be used to create a genuine emotional connection with listeners. So your stage fright tension is a symptom of something that is right with you – you are sensitive! Use your sensitivity to be real with listeners adn tehy will fall in love with your authenticity. Best of success!