Looking for a word for…

I posted on twitter yesterday looking for a word. Here's what I wrote:

I need a word for someone who is always very busy and doing work, but adds no value (It's a distant cousin to slacker, but a more active kind of unproduction).

Can be a real word, or made up – received about 15 suggestions:

busy body
unproductive
bureaucrat
program manager
wheel spinner
Frantic fluffer
drone
Workaholic
Troll
Frolicker
Oxygen waster
Middle manager
Busy-bee
Frantic Zero
Stacker
Seat warmer
Stationary duck
Politician
Keener
Stroker

Any other ideas, or votes, dear blog readers?

Related posts:The mystery of the front row
The manager that's never there
New essay: How to survive a bad manager
This week: you make the call
No secrets: new project management blog