Howdy all, new to the forum, and hoping to contribute in a meaningful way.
Lest we forget, we shouldn't leave out the Northover Projector (or officially, the "Projector, 2.5 inch") and the No. 76 Special Incendiary Grenade.
http://en.wikipedia.org/wiki/Northover_Projector
Basically, get a big piece of pipe, mount it on a wobbly tripod, put a screw in breach, and use a charge of black powder touched off by a cap from a child's cap gun. The projectile of choice was the No. 76 grenade, which was basically a milk bottle stuffed with white phosphorous and gasoline.
What's not to like? A projectile that has a large chance of going blooie in the breech and spraying phosphorous everywhere? A tripod that had a chance of randomly bending during firing and sending the projectile flying off into God knows where? A weapon made from drain pipe? It just shows the desperation Britain had reached after Calais that they actually produced these things in quantities.