You've got plenty of off-the-shelf options these days:

http://www.musiciansfriend.com/search/search.jsp?sB=r&question=laptop+stand

I've always used the simple heavy duty black Music Stand by tilting it back to the near horizontal and then tightening the bolts well. A black "bungee" cord to make sure the lappy doesn't leave the stand and it works very well indeed.

I like to fold the laptop out flat when doing that, although you don't necessarily have to do that.


--Mac