Recently I've run across two JMP Wish List items that could be satisfied by a JMP Add-in written in JSL. Either of these would be a great way for you to develop or exercise your JSL skills. There's nothing like a concrete project to chew on to help you learn something new.
If you're looking for a project these would be great.
Fishbone/Cause-and-Effect-Diagram to DOE Transfer-Tool
This one is the slightly more complicated of the two. The poster is suggesting that the Ishikawa diagram would make a great input into the Custom Designer.
Find/Replace Chart Name within Report/Output Window
The user here wants to find and replace within outline nodes (possibly other display boxes) in a report. @DaveB has helpfully provided a JSL function to do the hard work. All you'll need to provide is a user interface to prompt for the search/replace strings. Turn it in to an add-in that works on the Current Report() and you'll be all set.