I created a very simple Android app that launches the Calendar app, at the New Event screen, with the start time pre-filled as the time on your device.
I wonder why the Calendar widget doesn’t have a New Event/Add Event button. That annoys me, too!
It only works with the Calendar app that came with Ice-cream Sandwich onwards, though, so you won’t be able to install this on a pre-Ice-cream Sandwich device.
As for my other app on the Google Play Store:
My first Android app live – DigiTech Patch Viewer!