Light weight C++ SAX XML parser
you can try https://github.com/thinlizzy/die-xml . it seems to be very small and easy to use
this is a recently made C++0x XML SAX parser open source and the author is willing feedbacks
it parses an input stream and generates events on callbacks compatible to std::function
the stack machine uses finite automata as a backend and some events (start tag and text nodes) use iterators in order to minimize buffering, making it pretty lightweight
I've used expat when I needed to parse XML. It's very light-weight (well, it used to be; it's a while since I've done XML stuff) and does the job.