Fixing links that move or disappear. I like presenting - with the overhead onto a white board and then use colored pens to point out items. Its like leaning over a student's shoulder and pointing something out to them - it is iterative, simple, quick, dependable. The quality of these gets better all the time. I don't show a lot of Web during class, but rather things I get from the web.
Publishers are great at supplying - material.
I am starting to find more that is suitable for food science. This is the best part.