Usually I use a slightly hacked version of txt2slides to make presentations. Today I've been making something that's not going to be webified anyway, so I figured I should play with the fancy technicolor tools.
Keynote is super neat, but there are a bit too many "hmn, how can I make it ...." moments that ends up unresolved. Still very cool though. I used PowerPoint once and this is just so much more fun. When I make it save the presentation as a bundle the files gets saved in a way that's more compatible with revision control systems than such files usually are.
The new version of Omnigraffle is bloody awesome. I've been using it for a couple of hours and there's no end to the "ooh, clever" discoveries. The earlier versions were useful; 3.0 is amazing. When you resize an element it'll show you which other elements have the same size as your current size. Likewise for distances when you are moving things. So clever; and I thought I'd need to use the grid for that sort of thing.