Time Management for Sysadmins mentions the Pimlical's DateBk software a lot. It is one of the finest time management software packages around. It was way ahead of its time
Sadly it was only available for the Palm series of PDAs.
Pimlical's equivalent program for Android is called "Advanced Calendar". Until recently the installation process was a bit... odd.
Now it is available on the Google Play app store. As a result, it is much easier to install.
Check it out here: