While many open source projects have bloomed into household names, lots of really good ones don't get much attention. IT World is out with an interesting look at 10 best (unknown) open source projects, and turns up a few projects that I didn't know about, including an application called Chordii that converts simple song scripts into mashups of lyrics and guitar chord tablature, and Virtual Moon Atlas, which is, as its title suggests, a very complete atlas of the moon. We've delved into little-known but useful open source projects before, too. Here are four unsung projects worth looking into.

Piwik, at left, is great open source web analytics software. When it comes to doing web analytics, it's beneficial to get as many views of your data as possible, so you can use Piwik in conjunction with a tool like Google Analytics or on its own.

Piwik's features are built inside plug-ins, and a community of developers contributes interesting plug-ins. It also has a very customizable interface where you can drag and drop the types of widgets you would like to keep an eye on regarding site metrics.

We covered Rockbox a little while ago, and it's improved since then. Rockbox is an open source firmware replacement for the standard-issue firmware found on music players ranging from the iPod to players from Archos, iRiver, Olympus and others. Check out the many players that it works with here. Many people swear by Rockbox, and it can breathe life into old MP3 players. It's essentially like having a more robust operating system on your digital player.

Prism is a free application that lets you convert video files from one format to virtually any other format. It's beloved by many people who frequently work with video, and lets you preview your output to ensure that the encoding is working correctly.