A rechargable "gun" with low range (similar to the mining lazer.) Instead of killing mobs, it would paralyze them as you could push them to your zoo 
. (In 1.0.0 Mobs don't despawn, therefore you can make a zoo)
Other stuff:
Unlike the mining lazer it flows a continuous stream of power. (taser = machine gun, mining lazer = one shot) This would be great for laggy smp servers.
it makes the same firing sound as nuclear reactors "on" state sound.
not as powerful as the mining lazer
?shooting machines will charge them (no real purpose, just for realism)
?You could also have it turn creepers into electric creepers. (like when they are hit by lightning.)
?crafted with a tesla coil + mining lazer + some cables.