Ruby Date Recurrence Library

 ice_cube is a recurring date library for Ruby. It allows for quick,
 programmatic expansion of recurring date rules. The API is modeled after
 iCalendar events, in a pleasant Ruby syntax. The power lies in the ability
 to specify multiple rules, and have ice_cube quickly figure out whether the
 schedule falls on a certain date (.occurs_on?), or what times it occurs at
 (.occurrences, .first, .all_occurrences).