Using the Work Area Bar (the lighter colored bar along the top of the timeline) you can designate segments of your movie and then, on the Share panel, click the checkbox that says Share Work Area Bar Only.
Along with your need, to Export/Share portions of the Timeline, the WAB, that Steve mentions, has a few other uses, as well. See this article for more details: http://forums.adobe.com/thread/869683?tstart=30
Thank you. This was extremely helpful. I did not realize that I can even use the WAB to cut down on my rendering times as well!
Some links you may want to visit
Importing Video http://forums.adobe.com/thread/1065281
Saving & Sharing http://forums.adobe.com/thread/1051093
Sharing for Computer http://forums.adobe.com/thread/1058237
Steve's Basic Training Tutorials... steps are the same for several versions
Right click PDF link in the upper right corner and select to save to your hard drive
-the page also has links to help pages for previous versions