When I was a security guard at Seagate I used to find it fascinating how people personalized their cubes. One woman in particular managed to make hers look like an old fashioned parlor, with lace doilies and plants and a nice rug. Another put cool buttons with various slogans all over her cube wall.
At my workplace I've had an altar for several years now with the encouragement of my employer--one dedicated to bringing in money for the company, in fact. I've also done rituals for the company. I know this isn't typical! But it's been cool. I think normally I would simply have a very small, unobtrusive symbol of my faith along with my family photos.
This subject came up as I looked around and realized what all I had in my office.