If Evernote and Keynote and NovaMind all got together and had a baby (never mind the mechanics, OK?), the offspring might look a little like Zengobi's Curio. A virtual whiteboard with presentation capacities, Curio has the organizational chops of Evernote, mind-mapping capabilities comparable to the best apps, and the ability to run slideshows with transitions, though with a limited palette.
Taken together, Curio is one fast-loading, responsive package with fantastic potential and tons of flexibility. If there's a downside, it's Curio's price: $100 for new users and $50 for upgraders.