I have 6 monitors and a silent computer (see my Virtual System). Putting a speaker on a desk is bad in the best of circumstances. Putting it on my desk is audio suicide. I would say the same for you.
Now what I do was called heretical by the folks here, but I know better. I have my speakers behind me without any obstructions. That is the most important thing (no obstruction)
I was discussing this with a friend of mine, who is actually building some speakers these days for recording studios in Tenn.
He had been in my office where I have the 6 monitors and heard my system. He also told me what I am doing is definitely the way to go over putting speaker on a desk.
I also tried to put the speakers on a shelf near the ceiling and angled down to the desk. This was rather good, in a relative sense (compared to on the desk). However, it was not as good as the sound coming from behind me.
My office speakers are the $1000 Magnepan LRS+ driven by a CODA #16 amp. The LRS+ provides a wall of sound and is really nice in a small room with my back to it. That wall of sound really helps me forget how I am listening to the music. I just listen and love it.
Vandersteen has a speaker that can go on a higher level. Vivid audio also has a monitor that can also be attached to a wall. I would look at that Vivid speaker if you are set on having the sound coming from above you.