As someone who gives a lot of talks with a computer as a visual aid - not "slide" presentations with Keynote or PowerPoint, but live demonstrations, where I'm doing and discussing something on my computer, whose monitor is projected onto a screen at the front of the room - I am ever cognizant of the need to optimize the audience's viewing experience. Such presentations can be surprisingly difficult to see, even on a huge screen. So, if my subject matter will accommodate it, I reduce my screen's resolution. In every application I intend to use, I increase the default font size if possible. I enlarge the mouse cursor slightly, and occasionally, to give the audience an even better view of a detail, I zoom the screen (for these features, see the Universal Access preference pane). With a utility such as Ultimate Pen, I might "draw" on the screen to outline an area I want the audience to notice. And now and then I use a cursor highlighter, such as Mouse Locator or PinPoint (which Jeff Carlson wrote about last year).
<http://www.snowmintcs.com/products/ ultimatepenmac/>
<http://www.2point5fish.com/>
<http://www.macchampion.com/pinpoint_ features.shtml>
<http://db.tidbits.com/article/07976>
A newly improved contender on the cursor highlighter scene is Boinx Software's Mouseposé. Mouseposé used to be effectively a one-trick pony - when you pressed a hotkey combination, it temporarily darkened the screen outside a circle around the cursor - and it didn't provide enough options to be useful to me. Now, however, Mouseposé 2 incorporates a couple of valuable improvements:
<http://www.boinx.com/mousepose/>
Mouseposé will now make mouse-clicks visible, in a particularly vivid way: a dot at the cursor hot spot for a single click or while the mouse is held down; the same dot, plus a circle around the cursor, for a double-click; and an additional circle for a triple-click. This is truly valuable for presentations, because mouse clicks are otherwise invisible, so that it's difficult to clarify to the audience what you're doing (in the past I've often used my voice, saying "I'm clicking this button... NOW").
Mouseposé 2 now enables hot keys commands for some additional functionality. Besides darkening the screen starting at a circle around the cursor, you can now, for example, use hot keys to increase or decrease the size of that circle, thus helping you focus more accurately on the area of the screen you want the audience to notice.
Mouseposé 2 is a major new version, and is not without its teething problems. For example, running the "talkthrough" animation, in which Mouseposé demonstrates its own features, caused me to lose my customized preference settings; and I had quite a bit of trouble getting my hot key settings to "take." Mouseposé is scriptable with AppleScript (that's how the "talkthrough" operates), but the example script included in the Help document doesn't even work; the key command, "start effect," is incorrectly documented; and the scripting dictionary incorporates the entire massive AppleScript Studio dictionary, which is pointless and confusing to the user. (The Boinx folks should have read my AppleScript book!) Most depressing, Mouseposé 2 requires Quartz Extreme, which means that I won't actually be using it for my talks any time soon, as my old, trusty portable lacks this enhancement; this seems a silly restriction, since previous versions worked fine without it, and surely the program could just optionally disable whatever new slick animation features employ it.
<http://www.amazon.com/exec/obidos/ASIN/ 0596102119/tidbitselectro00/ref%3Dnosim/>
Mouseposé 2 is a universal binary and is a 2.6 MB download; it requires Mac OS X 10.4 Tiger and Quartz Extreme. It costs just $10, and can be run unlicensed as a demo which quits after five minutes.