Shiny is a good one, as is “sudsy.”
Copacetic (sometimes more “hunky-dory” than “cool”, but a – well – copacetic word)
fab and gear – height of Beatles popularity in the 1960’s
gone – one example of jazz slang on the linked page
the bee’s knees, the cat’s pajamas – 1920’s coinages
And let us not forget:
DYN - O- MITE!!!
But I thought we wanted to forget it.
Didn’t we want to forget it?
Jim
“Da bomb” had a brief life, meaning “the best.”
Jed Clampett had some folks saying “Hooooooooo, doggies!” for a while, when *The Beverley Hillbillies was current.
Better yet, “the shizznit.”
Whatever happened to “the bee’s knees” and “the cat’s pajamas”?
I first heard “bitchin’” in the early 60s around the same time as “boss.”
I heard “neato” and “keen” late 50s as well as the short-lived “zorchy”
I’ve heard a recording of Symphony Sid use “gone” while talking to Charlie Parker in the 40s (“real gone music”) but don’t know if it’s from earlier. When radio DJs are trying to sound “hep,” that’s usually a sign that their slang is years out of date.
also from the jazz era, “the most.” The most recent usage I can think of was by Jamie Foxx in “Ray,” when he said, “Is that Art Tatum? He’s the most!”
I can remember my cousins saying “sweet” in the early 90’s. Things like that always seemed to migrate from north to south. Took several years.
What about “awesome”? I’ve heard some of my peers say “sick” for “cool”. Personally, I just say “rad” and get weird looks. 
And fictionally speaking, Adams’s immortal “hoopy.”
One hoopy frood, that Douglas Adams.
groovy
decent
Or just “dece”.
I had a friend in high school that like the word “hip”. If it was cool to you, it was hip to him.
“Chill,” as the New Englanders say, but I’m not sure of the decade.
And I love Art Tatum! 
if you’re going there, might as well go for the superlative form
“wicked chill”
Hm, so dece isn’t a local thing. It was popular among some guys I knew in high school, but I didn’t realize it extended beyond that group.
Let us also not forget:
Jake
“Jake” is a favorite term of our much beloved Rue DeDay and is also used a lot in MMP therads. I think it’s more of a 40’s term.
These are all excellent - thank you so much!
Does anybody know any equivalents that date from earlier centuries? In this case I suppose it wouldn’t even have to be slang, but perhaps just archaic.
Probably ordinary suerlatives - as slang did not come into common use until “the Jazz age” of the 20’s
But let’s go the other way - negative words?
bogus
square
the pits