http://www.math.com/school/subject1/lessons/S1U3L1GL.html:  This site is a good resource for teaching factors. Students could also visit this site in the computer lab and go through the 4 sections of the lesson -- "First Glance" "In Depth" "Examples" "Workout"
http://www.mathsteacher.com.au/year7/ch03_prime/prime.htm: Interactive Maths Series By G Rehill and P Rehill--Full set of webpages going through Multiples and Factors.  It concludes with Problem Solving questions and Projects.  (http://www.mathsteacher.com.au/index.html The interactive mathematics software contain comprehensive chapters with numerous examples, exercises and millions of questions with complete solutions and reasoning
http://www.learner.org/channel/courses/learningmath/number/session6/part_a/: a 75 minute lesson on Models for Multiples and Factors

http://www.libraryvideo.com/streaming.asp?sku=K6450:  A 3:00 minute video stream about multiples and factors.  Entertaining and different way to present multiples and factors to students.
http://cuip.net/~jhammond/math/4.1.ppt:  A very good powerpoint presentation about Multiples and Factors.  Requires NO revisions for use in the classroom.