I was thinking of making a suggestion on the forums, since by the next update, you can launch spawn eggs from dispensers and have them spawn mobs.
First off, through survival and creative, you have two different spawn eggs.
The survival spawn eggs, you have to craft them. They stack up to 16, could be thrown like a regular egg and are consumed on use. The eggs have a 45% chance of actually spawning the mob.
The other, the creative spawn egg, can only be obtained through creative mode.
To craft the egg, I have three alternate ideas. The first one is crafting it.

Method #1: You use the monster's most common drop (Zombies are rotten flesh, pigs would be raw porkchops).
Method #2: You craft an empty spawn egg, which doesn't spawn anything. You have to cook (or 'brew', whichever you prefer) the regents into the egg for it to become the spawn egg.
Method #3: POKEMON. You use the empty spawn eggs to capture the essence of a mob, and then have a 45% chance of being able to release it when the egg breaks. Hostile mobs will become friendly, and attack other hostile mobs.
What do you think?