An adjustable desk platform can include: an upper platform defining a substantially planar work surface; a base located beneath the upper platform, the base defining a bottom surface without legs that is adapted to sit on an existing desk; first and second sets of arms coupling the upper platform to the base, wherein the first and second sets of arms are adapted for movement of the upper platform substantially in parallel with the base between a fully raised position and a fully lowered position; and a user-operable locking mechanism associated with the upper platform, the locking mechanism adapted to releasably lock the upper platform in the fully raised position, and in at least one intermediate position between the fully raised position and the fully lowered position. Other features and embodiments are discussed.