http://www.globalguideline.com/interview_questions/Questions.php?sc=C_Sharp_Programming_Language_Interview_Questions_A&page=6
In this URL, a user sees on the left side a Twitter picture move. How to do it. What’s this technique name? How to do that?
Try to search for floating menu.
There are two types: with fixed and absolute positioning. If you want similar animation as in the example then go with absolute. And if I remember it right IE6 has some issues with fixed position.
Alternatively you can go with jQuery, here is a good example with sources.