Granted: Everyone is now united under the new group: Eminescense. A flavorful mix between Eminem and Evanescence, normally the population at large would hate this, but due to the plague that recently ravaged 85% of Earth population, effecting everyone with an IQ above 90 and most with an IQ above 65, this is easily done.
I wish that the electromagnetic spectrum were inverted.
Your wish is my command!
Plants hate you forever before they all die horribly. Seems they didn’t take to the change all that well. Don’t worry, you won’t regret it long.
I wish I was an Earthbender.
You’re an Earthbender. However, you can only create 150 foot wide, 10 mile deep holes directly under your feet. Enjoy the fall.
I wish The UNC Tar Heels would win this year’s College World Series.
And they do. Sadly, the ensuing NCAA investigation closes down the entire athletic department.
I wish for a foolproof spam filter.
You shall have it, Master!
Behold the awesome power of your Ultimate Spam Annihilator v9.9. It’s become the challenge of challenges to penetrate that mother hustler… soon the virus-writers have decided to leave the easy meat of Vista alone to focus on testing their skillz against your setup. These guys are basement-dwelling dweebs and virgins-for-life… but they’re no fools.
I wish the djinn who started this game was forced to watch ‘Crossing Over with John Edward’ on a continuous loop for sixteen years straight… the same episode.
Sure, done… say, you’re not going anywhere, dude. Those nachos don’t serve themselves, not if that crazed djinn has anything to say about it - and he does, he’s a djinn, see? Well, you will.
I wish to be shot by a jealous husband when I’m at least 90 years old.
The day after your 90th birthday, you discover that your wife has been fooling around with pretty much every other guy in the nursing home. You are consumed with jealousy, and in a fit of despair you put a shotgun between your teeth and blow out the back of your skull. It doesn’t kill you instantly, but you do, eventually die later that day.
I wish I had a good singing voice.
Ah, the dulcet tones of the castrati…
I wish I could stop procrastinating and get back to writing already! 
You go back to the keyboard, and are compelled to write:
No beer and no TV make Enfant Terrible go crazy…
For 999 pages worth. Your wife finds what you’ve written while you take a potty break (where you scribble said saying on the toilet paper with your own blood-from compulsively scratching your back), and she surrepetitiously gets in her car and drives away to visit her divorce attorney.
I wish they’d make a completely 100% faithful movie version of [del]The Shining[/del] War and Peace, if just to shut up all those who bitch about movies not being exactly like the book they came from…
100% faithful it is - not hard, when the whole movie consists of some geriatric reading from the book.
I wish I had 1337 haxx0r skillz.
You have all the haxx0r skills you could ever want.
Sadly, you’re hit by a bus and put in a coma long before you get a chance to use them.
I wish the forum was red and white, instead of blue and gray.
Done! The forum is red and white. Something must be wrong with your eyes, though, because it still doesn’t look any different to you.
I wish that all of the people of Earth could live in peace, with everyone enjoying democracy, liberty and an environmentally-sustainable market economy, until the heat death of the Universe.
Granted, there is a nuclear war that devastates Earth, and the last three individuals left never meet each other, being stuck on different continents.
But, on the plus side, the nuclear war makes them immortal, so they have until the heat death of the universe to consider how lucky they are to live in perfect liberty.
(I like corrupting wishes by murdering everyone.)
I wish for an unlimited supply of lox and cream cheese on toasted everything bagels.
Granted. The limitless supply collapses into a black hole, taking you and everyone else with it.
I wish I could write in a manner than expresses my thoughts adequetely.
Granted, but until the day you die all you can think about is Meatspin (NSFW, don’t google it) or the Badger Song.
I wish that all doors opened automatically when you walked up to them.
No problem. They all open automatically when I walk up to them. You still have to open them for yourself.
I wish I had my choice of any job.
Granted, but the pay will be crap.
I wish Tom Cruise was caught sucking a dick on camera.
The next movie starring Tom Cruise, with Nicole Kidman as a private detective / love interest / femme fatale, will have the requisite kissing scene.
And the movie will flop at the box office, killing Ms Kidman’s movie career.
I wish for every violent plot against the family of Barack Obama to fizzle, fail, get chickened out of, be disrupted by law enforcement, or otherwise come to naught early enough that Sasha and Malia are never in imminent danger. (Corrupt THAT, if you dare!)
Your wish is granted. However, a Secret Service agent accidentally steps on Bo’s tail in foiling one of the plots. It hurts the dog for maybe ten minutes.
I wish I could write better poetry.
Granted - you can now write the most beautiful poetry imagineable. However, you can only write it in a language long dead, and neither you nor anyone who reads it will be able to understand it.
I wish my work week was only two 8 hour days.