Amethystium is good.

Simon Phillips - Protocol II & III

Live performance of Catalyst from Protocol III.

Kind of Blue by Miles Davis
Time Out by Dave Brubeck

Not the kind of records you let them playing on the background while doing stuff, but give them a try - if you don't listen to jazz music at all, they may work for you. They may even make you a jazz music lover.. ;)

Red Hot Chili Peppers have a few good instrumentals, Pretty Little Ditty being my favourite (can't link it as I'm in my phone, and lazy), can't remember the names of the others off the top of my head though.

Kraftwerk's Autobahn is the first album that comes to mind.

Call of Ktulu by Metallica and it is misspelled deliberately for reasons supposedly related to the lore

https://www.youtube.com/watch?v=t1RTgznup5c

Anesthesia by Metallica (Cliff Burton's bass solo)

https://www.youtube.com/watch?v=GhFMMiTmHb4

Also, here is a Nordic-style folk song called "Land of Eternal Winter." I'm not sure who the artist is but he or she must be really talented.

https://www.youtube.com/watch?v=-ZXlQlDsSuI

Oh man. Great suggestions. Time Out is pure rhythmic genius.

Yes indeed! And rhythm aside, mr Desmond - forgive my use of slang - kills it with his great melodies on the sax. It's simply a masterpiece, nothing less. :)

seconded

I was about to come give the same link

https://youtu.be/8iMMoGuUxks

apocalyptica is great too!

also "Third Eye Open" is a string ensemble playing Tool songs


also, if you are able to find their music: "ANIMUS"

Game soundtracks... depending on your library you should have a number of those. Most are instrumental or "inarticulate singing" and they cover a wide range of styles - classical, upbeat, rock/metal, spacey, some jazz...
I find film soundtracks most of the time too demanding to listen to them while working.

Other than that I can recommend Autechre if you like minimalist electronica or Boozoo Bajou for very laid back, yet stimulating downbeat lounge/jazz/blues/funk mix. Or ES Posthumus (known from the Cold Case TV series intro).

Also Dead Can Dance has some great instrumental/"inarticulate singing" pieces, but they also have a lot of songs with lyrics - so it would be up to you to create a "best of for working" mix. DCD in general is a treasure trove for all kinds of occasions - also great for finding "mood music" for PnP RPG.

I'll echo this. About the only instrumental music I listen to except classical.

Poppy Ackroyd is a personal favourite of mine when it comes to instrumental music - it's mostly piano, but she also plays the violin in a few tracks. She has released two albums so far; if you like what you hear in this video I'd recommend you to check out both.

I am also a fan of Valgeir Sigurðsson, I especially enjoy his latest (2012, so it's been a while now) album. Here is a track off it.

I also really like the album Here Be Dragons from The Kilimanjaro Darkjazz Ensemble. Despite the name, their music doesn't have much to do with actual jazz, it's more like dark ambient with a few jazz elements.

EDIT: I just read that you are actually looking for something more upbeat, (shame on me for not reading through two sentences properly...) so the music I posted might not exactly be what you are looking for...In that case I'll also leave this here: We Can Make The World Stop

Anything from Animusic.

Here are some of my favorite instrumental rock groups you should check out:

My Sleeping Karma

Monkey3

Ozric Tentacles

Hidria Spacefolk

The piano guys, although not all of their work. But couple of their tracks I do use for motivation.

https://www.youtube.com/user/ThePianoGuys