Thats really impressive 
Speaking of a capella there is a group called The Real Group that use their voice for all instruments etc. Hereis a video (dont mind the lyrics, I post it as an example for the beatboxing etc.)
/me escapes the thread 
Hmm, The Real Group has some good songs; shame most of the videos are crappy phonecamera recordings though 
Another quite nice a capella group is the German “Wise Guys”.
Though most of their repertoire is in German, they also covered the English Mad World (covered by the Wise Guys)
I kinda prefer their German songs though, such as Denglisch & Schiller by the Wise Guys
Especially Denglish is funny, as they sing about how the English language is slowly taking over their native language. Schiller is funny because it is a parody of Michael Jackson’s Thriller.
They also have a song about Facebook.
My final suggestion would be Wise Guys - Radio since it has a heavier emphasis on providing backing vocals/instruments with their voices.
Edit: okay, one more: Goldeneye by the Wise Guys
How could I forget about ‘Star Wars (John Williams Is The Man)’ a cappella tribute medley - Corey Vidal and Moosebutter
I’ve been playing piano for about 7 years and violin for almost 4 and nothing amazes me more than This instrumental cover.
I’ve been really enjoying the Korg iElectribe synth app on my wife’s iPad recently. Some of the sounds are just deliciously bizarre, when you manipulate the effects dials just right within the flux of the beats, riffs and chops. 
Holy crap, Koco. That trio is amazing. Very beautifully done. Sorry I haven’t been around here much. Here is something I know Wyvern likes to keep you all company. HERE
LOL…found it! The creme de la creme of synthesizer apps 
pause for effect
My friends, I present prestidigitous hand flourish the Korg iMS-20 analog synthesizer app for the iPad…a complete recreation of the Korg MS-20 analog synth, an analog sequencer, a drum machine, a mixer, and even Korg’s Kaoss Pad technology all right there waiting behind the exquisitely smooth glass of the iPad’s touch screen. I cannot express all the myriad ways in which this piece of technology rocks…but it does, mes amis. And you don’t have to be a musical genius to enjoy the voluminous depth of what this living, breathing creature has to offer…literally an infinity of electro bliss 
Highly recommended for any Pad-heads out there who like music-making apps
So, as for the invisible piano thing that doesn’t exist anymore, here is how to explain how it was “invisible”. I introduce to you all, the Dancing, Talking, Yamaha Piano.
SPOILER - Click to view
His invisible one wasn’t programmed, though, just recorded.
Not really because of the instruments or the music, but more for the pretty cool visualisation of the score 
youtube.com/watch?v=RctgRPkAOkA
XD That visualisation is EPIC. I wish they would do that in more classical videos. We need more musics!
FiXato’s link reminds me of Audiosurf .
In any case, out of all the instruments out there, I find certain fondness in string instruments, more specifically the violin. To a lesser extent, the guitar as well. I developed this particular fondness when I first listened to Michal Jelonek - BaRock. I started to listen to more music in general at that point. Michal Jelonek is still one of my favorite composers to this day.
XD Nice. Violin has always been one of those instruments I loved so much I wanted to learn, but never got a chance. 
But that’s just sexy. Silly Dr Who fan
I’ve been playing guitar now for almost 2+1/2 years, and I can say with confidence that its something I’d like to do for the rest of my life, but technology will always be my dream career. I’m good enough at playing, I can draw crowds of pedestrians when I practice at the local guitar center, that’s always fun 
At any rate, check this guy out, he makes some pretty crazy instrumentals all surrounding the guitar, he’s a legend IMO 
Heh, pretty neat I can recognise quite some metal band influences in that
While I don’t think the end result is very good, I do think Tubular Bells by the Brooklyn Organ Synth Orchestra is a pretty interesting video as it shows quite a lot of vintage keyboards and other curious instruments: "Filmed and Directed by Amy Hobby. Edited by Tony Zajkowski. Over 20 different NYC female keyboardists playing vintage keyboards at Joe McGinty’s Carousel… "
So many posts and links here, I’ll check them out later when I’m with better internet
I loooove different/bizarre/unusual instruments! and instrumental music as well.
I’ve been playing guitar for over 10 years now, and have composed some simple songs (all in my garden ) but I haven’t played much in a while now and I’m low on inspiration…
I’ll just leave this link.
EDIT: Probably my favourite instrument.
EDIT2: just realized the exact same video posted in my first edit is on the first page facepalm
Oh man. I just fell in love with the Les Petits Chanteurs de Saint Marc chior. And this song they sing called Vois Sur Ton Chemin. It’s very beautifully done, and I just watched their whole concert…
Oh gods Fix! That was so sexy that I just had to watch the Zelda Medley. Omg when she did Ride of the Rohirrim into Uruk hai at like 1:11. O_O