QuickMail Conversion Tool
One of my first projects as a consultant writing a Cocoa application for MacOSX. I was approached by Chapman and Cutler, LLP because a friend of mine who was the manager of the Applications Development group had seen some articles I had written for oreilly.com on adding scriptability to Cocoa applications. (The articles are here, here, and here, if you are interested)
Chapman was a law firm that had been using macs for years, but they were about to transition from the classic MacOS to MacOSX. They used QuickMail Pro, a nice email application that also managed contacts, but it was not going to be available under MacOSX. Apple had their own Mail and Address Book applications that came with the new OS, but there was no easy way to export contacts from QuickMail Pro and import them into Address Book. So they faced the prospect of having to spend thousands of man hours moving contacts from the old system to the new one.
They hired me as a consultant to write a utility that would read in the exported contacts from QuickMail Pro, but this was still a laborious process. So, I reverse engineered the binary data files that QuickMail Pro used to store contacts and was able to create a conversion utility that automatically scanned a directory looking for those files and then added those found groups and contacts to Address Book directly using the new Address Book APIs. What used to take well over an hour and take many steps had been reduced to a single step and only a few minutes.