TouchBase Calendar is a 1-Touch SMS, Calling & Maps for your iPhone Calendar. It syncs with the built-in Calendar, so you can continue to use it has your main calendar. What TouchBase does, is make it easy to send a text to the person you're meeting, or get directions to where you're going, or push back your meeting by 15 minutes - with one touch.
I've played around with TouchBase Calendar a bit and it's pretty cool. I tend to always be running late to where ever I'm going, so being able to quickly send a text to the person I'm supposed to be meeting with is really nice.