So your favorite band came through town, you missed the show and now your friends are all telling you how killer it was? Have no fear, a pair of grad students have gotten fed up and have developed a delightfully simple tool for keeping track of both your MP3 library AND your favorite band’s tour dates so you won’t miss the next killer do. The tool is iConcertCal and it’s a free iTunes plugin that monitors your music library and based upon your most playlist, generates a personalized calender of upcoming shows in your city. THe interface mimics iCal and is available for both Windows and Mac OS X.

Download: iConcertCal

So Twitter is our new fun obsession and what better way to enjoy a newfound hobby is there than to find all the free and open source software you can for it!? NONE! Twitterrific is a light and fun little application that lets you easily publish “tweets” to your Twitter account or read tweets from your Twitter contacts, all while stylishly occupying a small spot of real estate on your Mac’s desktop. Let your friends know what level your World of Warcraft character is or how badly you want the iPhone you’re reading about without having to leave your desktop!

Download: Twitterrific | Twitter