PowerPoint

Microsoft Office is one of the most ubiquitous packages available for organizing and sharing information.  It's most likely you have PowerPoint on your computer.  There are versions for both Mac and PC.

I'm not going into too much detail about this resource:  I assume you're either familiar with it yourself or you can find someone nearby who can create a PowerPoint presentation.

My only advice is that you run through the presentation and figure out what you want to say:  awkward pauses when you search for words or misspeak.  There's a notes window you can use to organize your ideas.  My trick:  when I run through the slides, I turn on voice recognition and create a script to use for when I "go live".

PointoFix

I love this for making quick screen grabs that I can mark up!  It's free but is written by a German group.  You have to load in an English translator, but it's simple to use, creates custom-sized swatches you can save or copy/paste.  If you get an error, the dialogue box may be in German, which is kind of fun.  It's available from http://www.pointofix.de/download.php.

Captivate

This software is amazingly easy to use and creates very professional looking final products.  It is quite expensive, and the output is rendered into shockwave (Flash) output. I believe you can also make movies and load them into YouTube. The advantage of using Flash output is that you can create interactivity very easily. You can create drag-and-drop exercises, multiple-choice questions, live links, and a host of other exercises.  It is available from Adobe Corporation.