Of all forms of subversion/protest guerilla gardening has got to be my favourites (do a google search), It's non violent, environmentally friendly, and has a healthy dose of humour about it, (and I'd love to give it a go.)
This instructable will show you how to build an electric seed hopper, and give suggestions on ways to use it.
Step 1: Materials
Here's what you'll be needing:
Small geared down electric motor
Piece of plastic (about 4mm thick)
Small jam pot
About 2.5cm diameter pulley
Some nuts and bolts of various sizes
A couple of washers
For the motor i used a nice small motor with an included gear box that was liberated from the auto focus mechanism of an old video camera.
The pulley was taken from part of the mechanism of a flat bed plotter (i REALLY wish I'd held onto the rest of it, it would of made an excellent x/y table for a simple CNC machine)
And the jam pot was "liberated" from a hotel (i guess they technically where free, but I like to think of myself as a bit of a badass sometimes.)