I found this tip while i was looking for Keynote ’08 reviews (MacOSXhints.com)
I am a scientist, who often has to use Greek and astronomical symbols. Before, in Keynote, it was necessary to open Edit » Special Characters, find the character, and insert it. Blah. But while playing with the trial version of iWork ’08, I found an additional small feature in the Preferences of Keynote 4: the Auto-Correction tab.
First check the box for Symbol and text substitution, then click the “+” sign below the existing list of substitutions. I can then add the special characters just once in this pref pane, and associate it with a special string. For instance, for the “alpha” greek symbol (α), I would associate the string alpha with that symbol (LaTeX users will appreciate).
Back in my slides, as soon as I type alpha, I get the α symbol![Rob G. adds: This panel is available in both Pages and Numbers as well. In iWork ’06, it was only in Pages. So I’ve been using TypeIt4Me to add my Keynote special characters. However, this is a more elegant solution for those characters I need only in Keynote.]