Snippet - diegesis

One idea I've wanted to play with is the use of fixed elements in a web page.  This can be extremely annoying for netbook and other users with limited screen real estate, but it could be interesting to explore what can be done with non-diegetic elements which are distanced by their behaviour from other elements within a site or page.  This is of course limited in usage to pages which have sufficient content to necessitate scrolling, which can itself be undesirable.  However, if you want to incorporate with elements which behave in unexpected ways, this could be a good technique.