I ditched Balsamiq mockups for Keynote Kung Fu.

As a set of templates and design elements, Kung Fu is really awesome. Definitely money well spent and the buttons/UI elements more or less cover everything I've needed to do.

To me, the question comes down to what software do you prefer to use for protoyping: Keynote, Balsamiq, Omnigraffle?

Keynote seems to have the best alignment, auto-positioning, etc and a really easy to use UI. The only downside (imo) is that Keynote only allows you to edit in 1024x768 or some similar canvas size, whereas Balsamiq lets you go as large as needed.

If you're already using Keynote, get it for sure.