Blueshift Software has several iPhone apps: Fabric Stash, Fabric Journal, Quilt Helper and they are working on others.
http://www.blueshiftsoftware.net/iph.../fabric-stash/
http://www.blueshiftsoftware.net/iph...abric-journal/
http://www.blueshiftsoftware.net/iph.../quilt-helper/
There are also apps for color selection, drawing, photo editing, one called Stitch Minder for knitting. Lots of them out there and more coming all the time!
Here's the Color Wheel one.
http://itunes.apple.com/us/app/color...320157374?mt=8