QGIS Workshop by Harvard University
This site by Lex Berman really gets my thumbs up and gives a clear set of tutorials. Presently, it covers:
I particularly like the one on Reproject because I have faced much query on this. They even made an interesting observation that "NOTE: QGIS 1.8 has charset problems. We recommend using version 1.7.3 (Oct 2012)" Let's hope it expands further on.