Seems like every time Star goes off a ski jump with her bike or finds a load of scrap iron to carry home, she needs a new bike wheel.
Here's how we straighten them back out in a hurry, or make "taco-ed" bike wheels from the bike shop's dumpster usable again.

This wheel is pretty bent. Notice how the joint is even coming apart.
Pix by Star

Step 1: Find a Hole

You can stomp a wheel pretty close to straight on regular pavement, but it's a lot easier if you find a way to do it without pushing on the hub. A hole in the pavement, a round table with a hole in the middle, the top of an oil drum, or a big iron garbage can are all good options. Cut a hole in a heavy piece of scrap plywood if you've got one handy.

As they say in Venezuela, "En tiempo de guerra, Cualquier hueco es trinchera."

I guess the city is planning to plant a tree here. In the meantime it's a good place to fix a wheel. Here I am uncovering the hole. Remember to cover it up again, this is a litigious society.

Step 2: Do the Stomp

This is the easy part.
Just go for it and stomp it flat.
Extra points for yelling and gesturing.

Step 3: Overbend

The metal rim has memory, so it'll spring back a bit after you flatten it.
So you have to bend it a little further than straight.
Put one or more sticks under the low spots and stomp again, a little more carefully this time.

After a bit of this the wheel will be mostly straight.

Step 4: Spin and Eyeball It

Spin the wheel and hold it by the hubs to see where the bent spots are.
You can mark them on the side with a pencil if you want.

Step 5: Repeat

Repeat sighting and bending.
Here's another way to arrange the sticks.

Step 6: Knee Technique

Here's another method to bend the wheel. Try out any technique that seems like it might work.
The wheel is now straight enough to ride again.

If you want it totally straight, now that you've got the tight kinks out, use a spoke wrench.
That only works if you've gotten the tight bends out.
Messing with the spokes is for gentler bends.
Tighten the spokes to move the rim toward that side.
Loosen a spoke to let the rim move away from it.
Hit the the spokes to make them ring.
The pitch of the tone you hear tells you the spoke tension.
If the spoke tension is totally non-uniform the wheel will get bent again just from riding it.