I need a diversion, and I was wondering. What would be a good library to write? It's somethings that I've wanted to do for a while, just never gotten around to. I was thinking about a lib for some of the methods that I often use, just much more generalized in some cases. Does anyone have any ideas for useful classes/methods to put in there?

A library for formatting dates. Every time I do that I have to create a new SimpleDateFormat, declare the format and use its methods. Have a class that does that. Also you can have a validation method that takes as argument a String and a format and checking if the String represents a Date. Also you can have a converter that converts java date formats to sql formats:
"dd/MM/yyyy HH:mm : ss" ---> "DD/MM/YYYY HH24:MI : SS"

A library for reading input from the keyboard.