MinML is minimal XML parser for java, intended to be used on embedded systems without using lots of system resources for parsing the document. Of course, it can be used for really simple XML documents on not-embedded systems too (it doesn't validate XML). MinML does not support mixed content or DTDs, which are read, but ignored. It has support for SAX1 and is available under BSD style license. At the time of this writing, there was no documents included in the package, so using MinML requires a bit hacking around to make it work, but there is nice example which helps a lot.
MinML is available from http://www.wilson.co.uk/xml/minml.htm