You have yet another way to share a slide show: iChat Theater. This sublimely cool aspect of Apple’s instant-messaging software lets you broadcast a slide show (among other things) to people with whom you’re chatting. They’ll see Ken Burns moves and transitions, and will even hear your background music.
And your friends don’t have to be using the very latest Mac OS X version, either—earlier iChat AV versions can also view iChat Theater broadcasts, as can compatible instant-messaging software for Windows.
Note: iChat Theater can broadcast instant slide shows only; you can’t broadcast a slide show project. (Workaround: export the slide show as a movie, then broadcast the movie using iChat Theater.)