Units convert is rather unique unit converter app - see the quick tour video on Vimeo. Its main feature is ability to collect your most used unit pairs, regardless of their category, and have them all accessible from the same screen. I'm not aware of any other app in this niche that offers it, and I find it the most compelling feature. I can search here and there for an obscure unit, but most of the time I need the same 5-6 pairs. It's a great iOS 7 app with: - custom fonts and colors (or use system, if you prefer) - dynamic type and auto-adjusting UI - custom keyboard with integrated calculator - full support for state restoration - custom appropriately used gestures/animations (add to favs is my favorite) etc. More details can be found on the web site, here's just the favorites screenshot and icon.