I got this little gem from "HyunWoo Kim"s blog, its awesome. Allows any adaptive family to follow the site contours of any topography given any 2D path. Its been working really well for us, we have been using it to place Site hoarding (fences) to coordinate site works and logistics and its fantastic!
Unfortunately, it seems to not like working on any newer version of Dynamo past 7.4(ish) and our office has now upgraded to v9.0. Its only the code block in the middle of the definition that seems to not work, it just runs for ages and crashes or i have to force close Revit. It usually only takes like 5-10 secs to run. Heres the video he posted showing how it works (http://plevit1.blogspot.kr/2015/04/railing-on-topography.html)
And here is the definition Test Site Follow
Any help is appreciated