I share a small office with 2 Postdocs (who are never here). In this desk is an array of papers, pens, computers, coffee mugs (not mine!) and a funny clock thingy! On my main desk (where I rarely sit) are post-it notes everywhere, more papers and folders, an old PC that has been dumped, a single pen (black!), a picture of the missus and a list of phone numbers.
Now if it's my home study, that's a different story altogether...