As you may know Key Curriculum was folded into McGraw Hill last year so now it's more difficult to find out what's going on in the Geometer's Sketchpad community. Fortunately, Dan Scher and Scott Steketee keep the spirit of this great piece of software alive with their blog where they present excellent ideas for teaching math with Sketchpad. The one pictured on the left is named Around and Around: Investigating Multiples.
for more details. If you are so inclined comment on their website and thank them for their efforts!