Recently I used Paint.NET to attempt a Funplosion logo (1).  I think the initial logo got the idea across, but the end result was pretty unpolished.  Disappointed by the end result, I decided to try to recreate my logo within Inkscape, a Vector graphics program where you create graphics by manipulating the image as a conglomeration of lines and curves, and doing things like "adding nodes".  Inkscape had a bit of a learning curve, but with the help of some tutorials and a healthy amount of trial and error I ended up with the current logo (2).  I'm very pleased with how it turned out - I think it looks a lot cleaner than the original bitmap image.  

1) An original prototype of the Funplosion Labs logo 

2) Current logo, after some quality time in Inkscape

Like other popular graphics apps such as Paint.NET and Gimp, Inkscape has a good number of tools and filters which are a lot of fun to experiment with.  Here are some variants I thought turned out particularly interesting... "realplosion" labs, perhaps?