So this is a running joke with my friends, feel free to add some, here’s some of the favorites:
The ability to sense far away lighthouses.
The ability to jump over houses that are painted red.
The ability to change your fingernail color (partially inspired by Family Guy)
The ability to become invisible when no one is watching (inspired by Mystery Men)
The ability to levitate one inch off the ground, but not the ability to propel yourself when you’re up there.
Fortelling the future - but limited to exactly one tenth of a second from now
X-ray vision, with a fixed focal length of ten kilometers, and no magnification
Super Ant Like Strength - can lift up to 30 times your own body weight, but only works with feathers
Super Hearing - can detect a pin dropping on the other side of the city, but it has to be Cleavland
The ability to turn oneself into sentient rock (but not back).
Knowledge of all movie showtimes in Düsseldorf, Germany. If a resident of Düsseldorf should end up with this superpower, he knows last month’s showtimes instead.
The ability to read 1800 words per minute combined with the reading comprehension of a third-grader.
The ability to hear fax machines and modems from a mile away.
The ability to speak with any creature on Earth, but only in profanity.
Encyclopedic knowledge of Spice Girls trivia.
The abilty to freeze water. (Power only works at the North pole.)
The ability to answer any trivia question. (A year after its asked)
The ability to say anything you say backwards.
The ability to use great mind powers to burn toast.
The ability to transform oneself into Peking Duck.
The ability to stretch like a rubberband… but only when confined into “fun size” spaces (usually about 1" x 1 1/2").
The ability to turn oneself into a sponge - but only when completely dry.
Supertaste (if its that close you probably aready know about the crime)
An uncanny ability to imitate moss.
The ability to sunburn faster than any other person on the planet.
Perfect mastery of Super Mario Brothers 2.
Ability to make your penis smaller.
The power to seduce anyone of the same sex (or opposite sex if you’re gay)
High energy gamma ray vision
Ability to win at any casino game that fades away the moment you turn 21
The ability to turn into a cold virus
The ability to melt butter.
The ability to summon sentient sharp objects that wish to puncture and slice you.
The ability to become invisible to butterflies.
The ability to sprout a prehensile tail, but your arms are ‘absorbed’ while the tail is out.
The ability to regurtitate at will.
The ability to become deaf and blind at will, without the ability to turn back.
Letterman had a “Top 10” list of these, waaay back in the day. Probably going back about 15 years now. The one I remember was:
My own personal favorite pointless superpowers are:
The ability to grow or shrink facial hair at will
Indestructable eyeballs
X-ray vision… but only through paint. No drywall, sorry!
Impervious to mosquito bites
That would not be a pointless superpower where I live… 
The ability to instantly determine the exact chemical compound of any poisonous substance just by ingesting a fatal dose of it.
The ability to go entire minutes without blinking.
The ability to come up with the perfect witty comeback, 10 minutes after-the-fact.
Magnetic colon.
And some day, the power to shut it off!
The ability to visit the Marianas Trench.
But only once for 20 minutes…
This one isn’t entirely useless… if nothing else, it lets you know when to duck… a significant survival factor.
The ability to detect the exact location of any 11920’s style death ray, after you have shot and killed by it.
The ability to pop balloons using the power of you’re mind.
The abiluty to instantaniously teleport to any location in the Universe, but only between 5:00, and 6:00 AM on Fuck It Days (the third tuesday of every other even-numbered month {Febuary, June, and October}).
back when i used to GM the old TSR game “Gamma World” (D&D after WWIII) i had a few “mutations” lined up simply for humourous effect…
“Useless Lycanthropy”; the ability to transform into a were-mouse, were-caterpillar, were-snail, were-crayfish, were-pufferfish, were-coral, etc…
for any of the “humanoid” characters with fur (tigeroids, etc…) i had a mutation defect lined up for when they misbehaved, for example… “Fear of fur”
…
the ability to camoflauge themselves any color (except plaid)
the ability to speak only in binary (or hex)
the ability to shapeshift into a ham sandwich
the ability to give yourself Lymphoma
the ability to emit lethal levels of gamma radiation from your toenails
the ability to breathe water (when on land) and the ability to breathe air (when underwater)
the ability to command the loyalty of bacteria (Acidophilous bacteria, Nitrosomonas and Nitrobacter bacteria)
the ability to translate the language of plants…into the language of hermit crabs
If you’re on the Titanic, & the ship is sinking, staying 1 inch in the air is ducky.
Not useless.
Zatanna.
'Nuff said. 
Invisible nose.
Indistructable nostril hairs.
The ability to taste music.
The ability to tie your tongue in a knot.
Ability to sneeze fart and burp at the same time without exploding.
It’s been Done --say hello to Mossman, of the Masters Of The Universe.
