I'm Not Even Winded

MOAR

Demoman class--
M79 Thumper: OMG, a real gun! There are images on the web. I think it can manage running on Grenade Launcher hand animations, but the actual weapon doesn't have a revolving chamber.
Holds 3 grenades that explode on impact with anything. This means Demomen can grenade-jump, and are more able against Spies, Pyros, and Scouts, the classes capable of avoiding the original grenades. But, the Thumper's grenades do 50-70% damage.

MIRV Detonation Pack: The dynamite shown in trailers of the beta. Except, they'll need some balancing.
First of all, if fires incredulously slow, since it has to wait for the end of an animation loop. So it's better for setting traps than on-the-fly bombing. (This is where the Thumper and MIRV can be combined very well). The initial blast will have a large radius, but not kill a Heavy in one blast. It should be able to take down a Scout, though. Also, the small dynamite sticks fly pretty far away in open areas, and don't do too much damage. The Demoman can only have one out at once, and can detonate the on he set at any time (maybe even in the air, raining dynamite sticks over the other team huddled around the Payload cart.)

Tonic Water: Doing the taunt will heal you, but the actual weapon does 30-50% damage. It's appearence is a skinnier, longer, translucent bottle.