here an interesting open source project I found that provides a rendering engine (html) for qti items. Its called R2Q2. You can check it out here:
http://denebola.ecs.soton.ac.uk:8080/r2q2/home.jsp
Its nice.
http://www.r2q2.ecs.soton.ac.uk/
http://qtiengine.qtitools.org/