Here is a collection of useful apps I have found for your phone and computer. Apps change all the time, so let me know if something is out of date or I am happy to add something you have found. I will also update this list as I find other useful apps.
I have not personally used all of these, but they all have high ratings and reviews. As always, use caution when downloading anything to your computer and phone.
Square Footage Master - Android app
The app comes with a camera ruler (as the one in the Advanced Ruler Pro app) and a body ruler that are very easy to use. It will also save the sq ft result to the memory card or you can send it to yourself or someone else by email.
Benjamin Moore Color Capture - Android and iPhone
Snap a picture of a color inspiration that catches your eye and instantly find its match from Benjamin Moore's more than 3,300 paint colors.
Builder Pro - iPad
If you’re a professional contractor or you simply like playing Bob the Builder during the weekend, Builder Pro is a great app to add to your iPad. Builder Pro provides users with building reference material, formulas and an integral contractor calculator to help you get the job done right and to code.
Credit Card Terminal - iPhone, iPad
A little pricey, but maybe worth it if you want the convenience of taking credit card payments from your phone. Watch for specials they offer for free set up.
Lapicida Design-in-Stone - Android, iPhone, iPad
Tool for designers and architects, or anyone wanting to redesign their interior. Explore over 200 stone swatch samples from the world’s finest collection of luxury natural stone flooring and wall tiles.
Interior Design - Android
Interior Design displays a slideshow of the most stunning examples of interior design from around the world.
Doors! - Android
Displays a slideshow of the most stunning examples of hand crafted doors from around the world.
Color RGB - iPad, iPhone, blog
Simple app that’s designed to help you find hex color values and hue levels.
Masque - iPad
Import images from your iPad, your Facebook albums or Flickr. You can easily edit your photos and add effects, create layers, use brushes and the very interesting multi-touch gradient tool.
ColorSnap - Blackberry, iPhone
Match real-world colors with paint colors and bring all your ideas to life. Get coordinating colors or create custom palettes.
Units by the TheMacBox - iPhone, iPod
Units can convert Area, Currency, Energy, Temperature, Time, Length, Weight, Speed, Pressure, Power, and Volume.
Push2Talk - Blackberry, iPhone, Android
This turns your phone into a walkie talkie. Great for communicating with your crew on the job.
Flashlight - Link to Android, but available for all.
This app turns your phone into a flashlight. I have used this one many times on jobs and even when trying to find the key hole coming home.
The app has everything you love about Houzz, including more than 80,000 original photographs from 13,000 architects, interior designers, photographers, contractors, and other design pros.