Keep track and organize lists of events. You will know exactly how many days since and days until any number of events. You can organize the events in categories. You can specify how often an event should repeat. The lists are color coded to tell you if an event is near or has past.
You can see days in number of years, month and days, weekdays of just number of days.
There is a widget too.
2.91 - Mar 24, 14 - bug fixes - If you have a newer phone get Days Since Pro - Free
2.9 - Oct 27, 13 - UI improvements and multiple category select dialog
2.8 - Sep 12, 13 - fix missing menu problems on some devices
2.7 - Sep 8, 13 - display style bug fix
2.6 - Aug 12, 13 - add widget and fix single quote bug
2.5 - Mar 28, 13 - default view option
2.0 - July 25, 12 - New interface based on user feedback
1.0 - Feb 27, 12 - Initial version