Is there an existing module out there for calculating recurring dates?
Something along the lines of the perl Date::Manip module.
Not sure if this'll do, but there's: http://runt.rubyforge.org . This is
my implementation of several Martin Fowler's doucmented temporal
patterns. I haven't done much with it in a while, but if you find it
useful, I'll gladly take it off the self and help you get it running...