Date / Time Library

While I am fairly new to MVD I am willing to set off on an adventure but wanted to make sure I wasn't duplicating someone else's noble efforts... to that avail I thought I would ask if anyone has developed a library of date / time processing routines?  I need to be able to increment & decrement all aspects of dates & times (hours, minutes, seconds, days, months & years.  While the xxxBetween routines are great and would also be used, I need to be able to do extensive date/time processing... has this bridge been crossed any anyone?

Regards,
Keith