While looking for a convenient way for storing some level data for a game I’m working on (more of that later), I came across this small C++ XML parser. Originally, I wanted to stay away from XML or other formats as they are overkill for the simple game format. However, this parser is both small (the Xerces parser is over 50 megabytes!) and easy to use.
In case you can’t find a download link on the project page: you have to email the author to receive the library (the page promises a direct download link in a few weeks). I think that’s actually quite nice, considering people who write free software rarely get the praise and attention they deserve.