[saluki]

TV for dashboards or maybe showing an HD camera feed of a cool direction outside your office, since there aren't any windows

Fathead wall clings (Star Wars?).

Custom wall clings relating to your company and/or stack/tech.

Paint areas on a couple walls with white board paint.

A plant or two that can live with just office lights would be a plus.

If your company has sales closes big deals have some lights or even a ding when one comes in.

LED lights inside crown molding installed a couple inches below the ceiling.

A startup here has some cool movie props (back to the future, pixar), star wars helmets, lego sets/sculptures, could be a nice addition on some shelves maybe.