TP grenades are pretty effective except for that dead zone at the top and bottom.
Right now I think the disposible idea works real well, I heard about aluminum bodied reusable co2 ones but I have a feeling they're expensive (and would suck majorly to get hit in the face with a chunk of metal). And I know the ABS ones are only good for clearing rooms and are expensive and some are prone to breakage.
I'd like to see some way to remove the need for a lighter on the TP grenade design.