Pinatas are a lot of fun to make and can be prepared quite a while ahead of the party (though at times between cakes, invitations, decorations and the zillion other things you'll need to do, it's ok to break down and buy one from your local party store*grin*.

General Paper Mache Instructions

Bird Pinata, Bat Pinata, Dinosaur Egg Pinata

Dora the Explorer -- round pinata (punch ball from the dollar store) with black crepe paper hair and painted on features -- check out the Rock Crusher Pinata for specifics on how to make a round pinata

Fish Pinata, Frog Pinata, Rock Crusher Pinata (Construction Theme), Pikachu (Pokemon) Pinata, Spider Pinata -- great for Halloween or Spiderman party

Super Simple Pinata -- this is the easiest (and least messy) version of a pinata I know. It's great for groups of kids.

Playing the Pinata Game.

Hang the pinata up from the ceiling. Each child gets a turn trying to break the pinata. Blindfold the child and give them a stick (a broom handle works well) -- make sure all the other children stand WELL back from the swinging! Turn the child around in a circle 2 or 3 times and point him or her in the direction of the pinata. The child gets to swing the stick 2 or 3 times.

Then another child gets a turn. When someone breaks the pinata, all the children get to gather the goodies. You might want to prewrap the goodies in bags so they don't get paper mache on them and so that each child gets and equal share -- this is especially useful when the children are of various ages.

TIP:

I use skipping ropes, to rope off a small circle inside a large circle.
The stick (and whoever is using it) stays inside the small circle. When the person's done using it, they have to put the stick down inside the small circle before they go back to the audience.
The audience stays outside the large circle
At most parties, remembering the rules of the circles becomes as much of a game for the kids as whacking the pinata.