(I atone in advance for this topic's platform-specificness.)
I was wondering if anyone who owns either iMockups or Omnigaffle for the iPad could pipe up with their thoughts and comments? I've been doing some very rough wireframe sketching using the free Adobe Ideas app, but have been looking at both of these apps as my next purchase.
iMockups is $10, so there isn't as much of an investment lost if it isn't an effective tool. Conversely, Omnigraffle is $50, so the wallet pain is somewhat more pronounced.
In general, I'd love to hear if anyone is actively using the iPad for design / UX work, and what applications you use.