Your library card is valid. However, the library only has these books:
The Straight Dope
More of the Straight Dope
Return of the Straight Dope
The Straight Dope Tells All
Triumph of the Straight Dope
I wish I had a more fuel-efficient car.
Here ya go. Note that you will never get another date so long as you own this wonderful 100 MPG little number (or your SO dumps/divorces you).
I wish I knew instantly whom my One True Soulmate is, and where she lives.
[Oh yes! Screw with extreme prejudice!]
You do–she’s six months old and lives in a tiny village in the Amazon rainforest where no white person has ever been. Her tribe are all headhunters and more than ceremonial cannibals.
I wish the weather could always be the way it is today, except for one night per week when it rains for six hours, midnight to six ayem.
Very well, the weather will forevermore be as it is today – on Venus’ north pole. Oh, except for one night per week, when it rains sulphuric acid for six hours, midnight to six AM. Park indoors!
I wish I had my dream job, tenured Professor of Criminology at a major research university.
Done. But a convicted multiple murderer whose cases you researched now irrationally blames you for his continued incarceration. When he breaks out tomorrow, he’s coming for you.
Hmmm. Maybe time for a little reverse psychology.
I wish the Earth was destroyed by a nuclear war.
Granted. However, a group of far right republicans (or far left democrats, whichever you wouldn’t like 
) learns about it ahead of time and gets away to another planet. They proceed to colonize it and the remnents of humanity that are left build a civilization in their own mold.
I wish I was less lazy and could keep my house as clean as I would like.
Congratulations your house now has 100 sq. ft. of living area.
I wish for a producing pecan tree growing in the yard.
Granted. The tree produces so many pecans that you have flooded the market driving the price down to nothing. Other pecan farmers sue you for millions of dollars and the judge agrees.
I wish I had another bottle of Redhook ESB.
Your wish is granted. Unfortunately, the blood bank won’t let you sell another pint for at least two weeks, so you’ll have to keep panhandling until then.
I wish I had a secret identity.
Wish granted… uh, do we know you?
I wish for peas on Earth.
The entire surface of the Earth is instantly covered with gazillions of peas in a layer half a mile thick, smooshing everyone. Nice going, dude.
I wish everyone who ever committed aggravated murder of another human being, as defined by Ohio law, would instantly die.
Dammit, now we have to dig up legal cites for this game? This is hard work, perverting wishes. 
Well, the good news is that you survive the first, catastrophic application of your wish - when all the previous murderers die. Unfortunately, by my reading of ORC 5903.02, the definition of murder, you’ve just caused a great number of unlawful deaths. On purpose, no less. And will be so adjudged. And once that happens, the next time someone commits aggrivated murder, you will also be guilty of it, for having been convicted of a felony and willfully caused the unlawful death of someone else.
So, ultimately, your wish will kill you, too.
I wish I could simplify the legal code. (I know just how ugly this will get…)
“If the law says that, then the law is an ass.” - attrib. to Dr. Samuel Johnson
The law is simplified. We now have the law of the jungle: kill or be killed. Human civilization collapses overnight into anarchy.
I wish anarchists at least had some sense of style.
Anarchists now have a very distinctive style; unfortunately, a key piece involves being covered in your blood.
I wish I were an astronaut.
Your wish is granted–bet you’re wishing you’d wished for a spacesuit, too!
I wish the dodo and giant auk were no longer extinct.
All of the other animals change into dodo and giant auk.
I wish for a hover car that I can drive anywhere around the world.
Granted.
Of course, “can” does not mean “may”. Whilst tooling through restricted airspace you are shot down, and leave an ugly stain on the landscape. The EPA will be talking to you.
(I’m surprised more alumni of the original “Corrupt Wish Game” haven’t shown up yet. Hi dere, Scuba_Ben. [This remark will doubtless prompt two other posters to this thread to carp, “Hey, I was there, too!” If so, maybe I should wish for a better memory.])
I wish my life were a bowl of cherries.
Your life is a bowl of cherries. All you get to eat is cherries. You suffer severe nutritional definciences and die a slow, horrible death.
I wish al-Quida had been destroyed before September 2001.
Congratulations, your life is nothing but cherries, along with a irresistable urge to projectile vomit every time you smell cherries. Which you’ll be doing a lot.
Gah, Annie X-Mas beat me to it.
Al-Qaida is destroyed prior to 9-11. Unfortunately, the Taliban develops nukes, and smuggles one into NYC on 9-11-01, which kills 250,000.
I wish I had the willpower to stick to a diet and lose 100 pounds by following it.