I know it's a list of desktop apps, but I just recently launched a quick reference (iPhone) app for iOS devs: http://www.idev101.com/app/ http://www.idev101.com

I know it's a list of desktop apps, but I just recently launched a quick reference (iPhone) app for iOS devs: http://www.idev101.com/app/ http://www.idev101.com/app/ The color picker is my personal favorite. It'll convert between hex colors, RGB and HSB. Plus it shows the UIColor code for whatever color you're previewing.