For your iphone/ipad... useful & fun...
1. Magic Plan - Take photographs of a room and the app will draw a floor plan of it (no AutoCAD experience necessary!)
2. Color Capture - Benjamin Moore's color match app. Take a photo and get the cooresponding BM paint that matches.
3. iHandy Carpenter - Transforms your ipad or smartphone into five useful tools: surface level, bubble level, plumb bob, protractor and ruler... great for when you want to hang a picture in a flash!
4. eDesign Assistant - Search among 36,000 different fabrics/furnishings from Kravet & Lee Jofa or snap photos and let the app choose a range of coordinating products.
Do you have a design app that you use? If so, please share!