My partner daicoden goes through a callback proposal for handling errors Sequel raises when saving a model. Does wonders in the refactoring department.

Encoding QR Codes with Ruby is a solved problem, but decoding is another story. There are several Java libraries that provide decoding functionality though, so wrapping one of them with JRuby is likely a good idea.

Nearly a week ago, Matt Aimonetti wrote an example on using MacRuby and NSUndoManager to implement undo functionality. This is a byproduct: an Undoable module.

Gregory House, M.D. uses Maglev to diagnose a patient. Results (and my experience implementing a Persistable module with Maglev) inside.