Targetting business use cases, there is a lack of support for calculating working days or as opposite holydays.
In the specific Chronology classe there are no methods to calculate specific floating holidays like the gregorian/ julian based Easter date like in ICU.
It would be useful to define helper methods to define an array or list of holydays, a formalism to define weekends (non working days). In business cases you could define a period (e. g. calculation contract durations, subscriptions and so on) applying to this formalism to get only the amount of days for this kind of timespan (considering the defined rules).
Unlikely to be part of Joda-Time. See http://objectlabkit.sourceforge.net/