Creativity Applications for the iPhone + iPad

Apps that encourage or help with creativity are becoming particularly popular on the two systems, especially with artists, web designers, logo designers , writers and poets.
So with that in mind, here are a couple of the best applications available for the iPhone and/or the iPad to help with creativity:

Idea Sketch:
Idea Sketch is a totally free app that allows you to turn your iPhone into the ultimate brainstorm notepad; turning the screen into an editable mind-map. No real functionality other than the basic mind-map program, but you wouldn't expect too much from a free application. This application is actually genuinely useful, and should be utlised just to see what new ideas, methods, etc. you come up with at the end of the session.

Moodboard:
This one's for the iPad, and allows you to make a moodboard featuring anything you want; videos, copy, colour charts, images, and countless others. Perfect for writers, designers and artists, you can put together a specific board for each logo design or project you take on board.

Sketchbook Pro
This is another iPad application, it costs a few quid but it's absolutely worth it. The application lets you paint, draw and doodle directly onto the pad using your fingers or the stylus. You can quickly and easily select your colour, type of brush, fill, etc. and it even features layers for more complicated illustrations, drawings for a logo, etc.

Things 'Things' is a project management application that also allows for detailed time keeping. Admittedly this one doesn't help with your creative output, but is extremely useful for creative freelancers. The app lets you keep track of how much time you're spending on which jobs, and also shows you which jobs still need doing. It's extremely useful for project management and even makes billing easier, particularly if you bill for your work by the hour. Again this one costs a little more, but would be genuinely useful to any creative freelancer.