I was just today looking at some examples of tracker use and stumbled on hum-gtk - a gtk music player that combines three very-close-at-heart projects together: gstreamer, vala and tracker. It's a simple app, the picture speaks louder than any description:
But the true greatness comes when you look at the source code of it. I dare you - do take a look at it:
You can see that you can make a decent music player (yeah, it's the 0.1 stage, so no-one is expecting a miracle) with just tiny amount of code.
Oh, by the way, I've published a new version of theme maker that has lot's of good fixes and font support and I'm now working on including icon support to the diablo.
 The screenshot is from the 0.1 version that was written on c. The code is still very neat, but not just vala. http://hum-gtk.googlecode.com/svn/branches/0.1/src/