Launch Center Pro + OmniFocus
After seeing this video, I immediately went out and bought Launch Center Pro for my iPhone-it's like "speed dial" for other apps.
To get an idea of how it works, consider the following example:
I frequently send text messages to my wife. Before Launch Center Pro I'd have to unlock my iPhone's screen, launch the iMessage app, click the address button, scroll down to my wife's name, then type my message. Bleh. Using Launch Center Pro, I push a single button and the app does the rest (launching the app, addressing the text message to my wife, and moving the cursor to the text input field). I have similar buttons configured to launch and configure TweetBot (my favorite Twitter client), as well as entering new calendar items using Week Cal.
But perhaps the best use of Launch Center Pro is having it interface with OmniFocus--as explained by Michael Schecter. After watching the following video, I was able to set up the Omnifocus actions within Launch Center Pro in about 10 minutes.
Enjoy!