Boundy is a bounding and constraining library for any comparable types; it is like Ranges, but with much more flexibility. Boundy allows for the creation of bounded and partially-bounded intervals -- or domains. Boundy allows for these domains to be intersected, creating a new domain, which can be acted on further. I originally wrote Boundy for intersecting date ranges for reporting, but it should be useable for any Comparable types.

A generic workflow definition framework.

Manacle will allow you to attach constraints to your objects that will persist across new instances of similar objects. As an example, you can constrain a Time object to always advance to the next hour. Then, if you add even one minute to that Time, it will snap to the next hour.