Text Anarchy will allow you to cycle through fonts, as well as a lot of keyframeable control over text effects. The link will lead you to a manual if you to take a look through the features and capabilities. Click the "Text Anarchy Resources" button to get you to the manual.
Joe's provided good solutions. I'd like to add the built-in Text Tool which allows you to cycle fonts (and other attributes available via the Character Panel, albeit manually, using the Source Text property.
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