There is already functionality in place in 7.17 that allows you to customize where/whether joins/parts/quits are shown in a #channel. It would be helpful to have remote control over this functionality. Writing a script to do the same thing isn't difficult but it's certainly much faster to have the program do it.
There are a lot of channels, for instance #ActiveTrader on FinancialChat and #CLGaming on QuakeNet and where you have tons and tons of people joining/parting/quitting. This would let you screen out some of this "event traffic."
