We have a scrollable div that has CSS hieght:40px;. Inside it are multiple LI height:20px
Updated with a working example http://jsfiddle.net/U4qyp/32/
I think .position() should do the job. It gives you the position of the element relative to its parent element. After you called .position() you can access the element coordinates using the properties top and left.
http://api.jquery.com/position/
The element whose top position plus its height is major than zero, is visible.
Here is an example of what I mean.
http://jsfiddle.net/U4qyp/10/