Type2Phone (US$4.99) is one of the most practical tools in my development toolbox. It emulates a Bluetooth keyboard from your Mac. With it, you type to your iOS device using your normal desktop keyboard.
While this may not sound like a big thing for many iOS users -- after all, the onboard keyboards and new dictation features streamline text entry -- it is a huge deal for devs and IT coordinators who have to keep typing similar things into apps and settings, over and over again.
For example, take Game Center development. You usually work with many different accounts, testing to see how access works for new users, for those with a good history of application use or for those who have unlocked certain achievements. In a normal debug session, you may sign out and sign in with various credentials dozens of times. Type2Phone makes that a practical exercise in testing instead of torment.
Or, take today. I was trying to set up a SOCKS proxy system and had to keep typing addresses for various configurations. Once again Type2Phone came to the rescue. It's so much more practical to type or paste longwinded URLs like http://10.0.0.1:8888/Public/socks.pac from my home desktop than to laboriously tip-tip-tap it on the phone or iPad.
Type2Phone was designed smartly, with re-use in mind. I long ago synced it to my primary dev units. Now, I just select each unit from the in-app pop-up list, and I'm ready to type right away.
To be fair, there are a few unhappy reviews over at the Mac App Store, but they describe situations (primarily beachballs) that I have not encountered, and I'm a pretty heavy user of the product.
For me, Type2Phone is an essential software component. My development life would be way harder without it. And that's why I consider it my Friday favorite for this week.