As the song says, “there may be many others, but they haven’t been discovered.” (or discahvered) Well, since the time that song was written, many others HAVE been discovered. Just so you know, it’s not a complete list.
What can a technetium scan do that a thallium scan can’t? And why does Tc have to clutter up the periodic table with its radioactive presence in the midst of all those other stable elements?
Perhaps you’ve heard of the Periodic Table table?
It was made by one of the founders/creators of Mathematica. It’s an interactive website, that allows you to explore his collection of all the elements. He has a write up for each element, and what they are commonly used for in today’s industry. Fascinating site… and awesome table.
Hey, don’t badmouth scandium!
Used in aluminum alloys to give a bike frame a supposedly “steel like” feel (that’s a good thing).
http://www.ciclisport.com/index.php?option=com_content&task=view&id=28&Itemid=27
Is osmium useful for anything? Other than as the answer to the question “what’s the most dense element?”
Osmium tetroxide is a common stain used in electron microscopy.
Iridium, bitch!
(I’m just saying. They’re both candidates.)
OK, since we’re now touting our favourite versions of the periodic table, heres mine - from the BBC spoof schools science programme Look Around You.
I’ve got iridium in the nib of my fountain pen. Next.
Huh? I wasn’t saying iridium wasn’t useful. I was saying it’s as dense as (or possibly denser than) osmium.
Anti-Hydrogen, which I beleive is created in supernova explosions, which we have no use for to date.
Ahem. See post #9.
And it’s the wooden Periodic Table table. 
I doubt that actual anti-hydrogen is produced in a supernova. Positrons and anti-protons, yes. But do they get together and form anti-hydrogen atoms?
Anti-hydrogen has been made at CERN in minute amounts. But the OP asked about naturally occuring elements, so I don’t think it counts. It certainly isn’t naturally occuring on Earth.
Osmic acid also makes vic-diols out of double bonds.
Is that good?
Yes. Industrial organic chemistry.
I’m used to thinking of OsO4 cleaving double bonds to carbonyls first and then they wouldn’t be vicinal diols anyway. What’s the conditions for the formation of vic-diols?
Sorry, I’m an idiot and realized it in the shower. Of course. OsO4 creates the epoxide and then it’s popped open making the vicinal diol. It’s early and I was thinking of periodic acid.
That’s about it for europium. I think we could live without it.
Back in 11th grade chemisty, I got randomly assigned Thulium (a blind pick out of a hat) in a “write a research paper about an element” assignment. It was really hard to meet the length requirement. I can still remember many of the papers I wrote in high school (15 years on now), but I’ve blocked that one from my memory…