I’d like to have the jumping ability of a flea, but the legs would make it hard to buy pants.
Sign me up for the wings and enhanced vision package please.
I’d like the ability to secrete poisonous mucus from my skin. So if I’m on an airplane, I’ll always ride wearing a tank top. And if someone next to me starts crowding, I’ll start ‘secreting’ on them! 
See how you like it when you start breaking out into hives! 
Hardcore burrowing abilities. Then if I was ever stuck for cash, I could do day-work for local contractors laying foundations, digging drainage ditches, etc.
Oh - and the ability to warble like a lark! (not a larch)
I’m another one who wants my prehensile tail, dammit. I told the Evolutionary committee that it would be useful again, once we got to a technical society, but did they listen to me?
I also want a pelt. I’m halfway there already, why not finish the job, dammit! :wally
(This way, when I die, my best beloved can have a nice rug to remember my by. <nodnodnodnodnodnodnod>)
Wings. Wanna fly without having to do it in lucid dreams.
I think you’re my lost twin. Gargoyles kicked ass!
I would like to have enhancements to my senses. So night-vision would be cool, as would IR and UV sensitivity. I would also like “super” hearing with greater range of frequencies. The regeneration thing sounds good too.
Dolphin-quality echolocation.
Electrical sensing ability from a platypus.
IR sense from a pit viper.
Ha ha.
Yayyy, I found a rookery brother.
Having a cat’s natural abilities would be nice… especially the ability to sleep everywhere and anywhere at any time you please.
And a prehensile tail too, but not very long. Don’t want it being stepped on.
If I had wings no one would ask me, “could I fly?”.
Yup, another vote for wings. Good vision/night vision would be helpful too, since I wouldn’t want to smack into planes or billboards while I’m flying around.
The grace, balance and leaping skills of a cat, and the ability to look like I meant to do that if I should screw up and fall.
Like when you use the wrong punctuation … yeah, I meant to do that.
I’d like to have a dog’s sense of smell.
Not only would it be cool to experience the world using a new primary sense, but I’d be able to creep the hell out of my co-workers… I can just see myself now catching my boss as he walks out of the bathroom, “Cup-o-Soup for dinner again, John?”
I immediately thought of a monkey tail, but then when I read your comment, I was sold.
I’ll have a set of gills, please. I’d love to be able to breathe on land AND under water. SCUBA tanks are just too damn heavy!
To all those who want tails: How are you going to sit down? Sure, most table chairs are fine. But think about recliners, couches and car seats? Sitting on it would have to get uncomfortable.
Anyway, here is my list.
-The horned toad’s ability to squirt blood from its tear ducts. I can think of no better way to deal with people who piss me off.
-The chameleon’s/squid’s/cuttlefish’s ability to change skin color. Granted, it wouldn’t be too handy for hiding unless I’m naked; but it would be really freakin’ cool. In fact, with a little practice, I could probably learn how to display pictures. And again, what better way to express disapproval than by turning completely red (coupled with a bloody shot from the tear ducts)?
-The electrical generation of the electric eel. Just in case somebody doesn’t get the point when I turn red and splatter them with blood. Could also be handy for charging cell phones and other electronic devices in an emergency, jump-starting cars, etc.
There’s a reason asses have cracks. 
The elephant’s thick skin would come in handy sometimes.
Half of the population has a similarly shaped body part on the opposite side of the body that it somehow manages to make it through life with.
I don’t imagine it would be much more annoying than it.
A body part whose name actually means “tail,” I might add. But it’s pretty rare that it makes it difficult to sit, it’s not as large as the proposed tails we’re talking about. Well, not for most of you.
Also, that body part is not what we sit on, most of the time.
Me, I’d like camouflaged skin, wings, a prehensile tail, and feet like an orangutan’s. Echolocation’d be cool too.
I’ll take the defensive secretions of a skunk. What better way to get rid of people?