As a reward for successfully integrating technology into my English & History classes, I have been assigned to teach info tech. I find the task of teaching without authentic lessons daunting. How to incorporate blogs, wikis, igoogle, google earth into a tech class without assignments???
Find out what they're doing in class and extend that with the technology you are teaching. I get the weekly newsletters from the teachers at my school and use the information in them to plan some lessons. In other cases, I go over the curriculum as a whole and create lessons associated with it. For example, my 3rd graders learn about plant life cycles so in the computer lab they created a slideshow in KidPix depicting the Plant Life Cycle.
Students also like doing things about themselves so do lessons based around current music or TV & movie reviews or just information about themselves.