“Cool” can mean simply entertaining or useful in a practical way.
Have you ever seen Skidboot?
My favorites are MOVE and OTHER ROOM.
While in college my dog used to stand right in front of the TV. I didn’t care where he went or what he did, I just wanted him somewhere else. So I taught him MOVE. Also works great when underfoot in the kitchen.
OTHER ROOM is similar - useful when cooking and/or eating - especially if you have company that isn’t used to big dogs around the table. Again, I don’t care what they are doing, I just want them to do it in another room. Generally ends up with them lying in the doorway, staring mournfully at us…
I’ve also taught each of my dogs to bring their ball right to me and drop it next to me in my chair. RIGHT HERE. Altho that also generally works for HEEL in non-ball-tossing situations. Yeah, I’m a lazy bum, but it they want me to throw the ball for them, no way I’m going to chase after them for the privilege.
I tend to only train my dogs to do a very few, useful commands. But I expect them to respond to the commands pretty darned well. One last thing, I always use commands that reflectthe way I talk. For example, HEEL doesn’t come naturally to me, while RIGHT HERE does.
I’ve seen dogs go to the fridge and fetch a beer. I’ve actually seen instructions on how to train it, but it wouldn’t work for us because we have the freezer below kind of fridge and he wouldn’t be able to reach. Anyway, teaching him how to open the fridge seems like a seriously bad idea. It’s only our thumbs and ability to opening packaging that keep him from eating us out of house and home as it is.
He does do puppy pushups - sitDOWNsitDOWNsitDOWN in rapid succession, which is really cute, and his downs are big showy ones.
A guy at a Highland Games had a cute little Rat Terrier wearing a kilt. When he said, “Ellie, sit like a lady,” she’d pose so that her kilt fell just right.
I’ve always thought this was pretty cool
That’s a dog that doesn’t pee in the house.
I don’t know why, but this stupid pet trick (Bailey “plays dead” in his master’s arms) made me and my parents crack up heartily.
I like “move” too, and “back” for walk backwards. It came in handy for cart pulling. I also taught one of the dogs to shake (not the paw thing, but shaking off the excess water on the porch, instead of in the house), and to unwind - sometimes I let them walk freely on a very long line, and if he tangles himself around something, he knows to go the other way, to undo it, instead of continually winding himself around it, or sitting and waiting for me to untangle him. Unfortunately, for all my trying, these last two things are lost on the other dog.
I had a cat who I trained to crouch and hiss dramatically and then run out of the room whenever she heard the words “Oliver Cromwell” or “Newt Gingrich”.
Some dog park friends taught their dog “crawl.” Way cute. 
The dog used to get under their bed and would have to crawl to get out, so they started associating that word with what she was doing and that’s how she learned it. I’d love to teach it to my dog, but she never crawls out from under anywhere.
That is funny.
When you raise guide dog puppies, you teach them “do your business” which causes them to pee or whatever right then and there. You can see the benefit to a blind person whose dog knows this. On excursions with the raisers’ club, it is fun to see ten dogs on a lawn all going simultaneously.
Dear lord. What would happen if I said “Dick Cheney” to it?
Doesn’t Yale train each Handsome Dan to play dead when asked if he’d rather go to Harvard or die?
Sometimes I wish I’d taught my dog this. It can take her forever to get around to doing what I know she needs to do!
While visiting Mallory Square in Key West, I saw a comedian/magician who had a dog for an assistant. The dog (appeared to be a retriever mix) climbed a ladder, WALKED A TIGHTROPE, no kidding, about 6’ off the ground, about 10’-15’ long, and exited a ramp on the other side.
Amazing.
Isn’t difficult - when he goes, act like he’s a three year old who went in the potty. Say your cue (we use “go potty!”) and give a big reward and throw a party.
Yeah, I know it can be done pretty easily. I just don’t care enough to do that training – yet, anyway.
Ducks incoming gunfire?
Some friends in Salt Lake City have a dog, Otis, who will fetch beer from the fridge. I think they have a clip on you tube.