Web Audio API Demos

More demos and details on how to run them here

JAM with Chrome Lets you play music live with your friends online.
Infinite Gangnam Style As Paul Lamere explains:

The app works by taking the audio and analyzing it with The Echo Nest analyzer to break it up into its individual beats. Next, an analysis pass is run on all the beats finding each beat’s nearest similar sounding neighbors that fall within a similarity threshold. Then, the song is played beat-by-beat – but with the added twist that any time we play a particular beat there’s a chance that we will transition instead to one of the beat’s similar sounding neighbors. For a pop song like Gangnam Style there’s lots of repetition so there’s plenty of good transition points. The result is that we can loop through the song forever with the song always morphing. .

WAVE-PD1 is a touch-enabled theremin-like instrument by Alex Gibson. Check it out on an iOS-enabled device, or a desktop browser.
Acid Defender is a web experiment, merging music-making with gameplay. All sounds (except for the snare and kick drum) are synthesized in the web browser and all sounds are sequenced in the web browser. You can either play the game, in which you must evade the "evil" red squares who want to destroy your notes, or you can play the jam mode with no enemies and more controls.

Demo courtesy of Patrick Borgeat (@cappelnord)
Pedalboard.js by Armagan Amcalar lets you play live guitar through an effects rack! The "live audio" feature is currently only available in Mac Chrome Canary and requires enabling "Web Audio Input" in "about:flags". Check out Armagan's blog post.
Bangarang Boomerang is Paul Lamere's latest creation from the Echo Nest. In his blog post, Paul describes it as: "My latest music hack is Bangarang Boomerang. It is a web app (runs in Chrome or the latest Safari), that lets you ‘drive’ the Skrillex song. You can freeze-frame the song on a beat, you can make the song go backwards beat by beat, you can advance through the song at double time, or triple time, and set bookmarks to let you easily jump to different sections of the song. It is a rather fun app that lets you feel like a musician, even if you have very little musical talent. "
StarBound A great live remix application with real-time effects. Demo courtesy of CopperWire / Tenth Circle Sound.
RemiX A very unique interactive remix application with great audio and visual design. Demo courtesy of Chris Coniglio. Also check out Sympyrean!
javascript motion detection Play the Xylophone using your webcam! Demo courtesy of Romuald Quantin.
Plink An interactive music application from DinahMoe. This one is multiplayer!.
ToneCraft A great interactive music application - demo courtesy of DinahMoe. More ToneCraft details here.
Guitar Tuner by Craig Spence lets you tune your guitar, voice, or other instrument. The "live audio" feature is currently only available in Mac Chrome Canary and requires enabling "Web Audio Input" in "about:flags".
ROCKETSHIP is an experiment in creating music which is specific to the browser. By recording each layer of the same song at multiple "energy" levels and using Web Audio to smoothly interpolate between them, users are able to fly at their own speed and create a unique and custom version of the song with each listen. Demo courtesy of Yotam Mann. .
Trigger Rally is an immersive open source racing game by Richard Davey. Please see his blog post here.
Skid A fast-paced racing game by Gamagio featuring 3D audio.
Technitone is a fusion of WebGL, Canvas, Web Sockets, CSS3, Javascript, Flash, and the Web Audio API.
Funklet is an interactive funk sequencer delving into some very interesting musical history. Demo courtesy of Rob Stenson.
TiberSynth Real-time audio synthesis and many-to-many vector mapping in the web browser. Here's a nice blog post describing it. Demo courtesy of Cory O'Brian.
Ambient Drone synthesizes an ambient sound texture using filtered noise. Demo courtesy of Matt Diamond.
Ring Visualizer By Felix Turner is a fantastic WebGL visualizer. Have fun interacting using the mouse and scrollwheel.
WebGL City By alteredqualia, Nick Royer, nofeedbak, and Erik McClure. Enjoy this rich 3D environment. To hear the spatialized helicopter, disable the music track "m", and enable the helicopter "n".
Mix.js By Kevin Ennis. Two demos let you apply a high-quality reverberation effect and control the real-time mixing of a song!
HTML5 Guitar By Dan Edington lets you strum guitar with room effects!
Bohemian Rhapsichord A Music Hack Day hack by Jennie and Paul Lamere. For more information see Music Machinery
Graphical Filter Editor Draw a complex filter and watch the visualization. Demo courtesy of Carlos Rafael Gimenes das Neves.
Angry Birds The ever-popular game now uses the Web Audio API, if available.
Multiplayer Piano By Brandon Lockaby. Play the piano with people from all around the world! github project here.
PlayCanvas 3D Positional Audio by Dave Evans of playcanvas
Sound Toy Design your own sounds with code and maths. Demo courtesy of Iñigo Quilez - please see his blog for more info.
AudioJedit Edit tracks from SoundCloud and upload a new creation! Demo courtesy of Tomás Senart - github code here.
Bytebeat HTML5 version by Gregg Tavares. It lets you write a musical function given only "t" as input. See Gregg's blog for more information.
Web Synth is a two oscillator synthesizer - demo courtesy of Aike.
Morning Star Synth is a monophonic bassline synthesizer controlled by a step sequencer. It features resonant filters, distortion, and a reverb - demo courtesy of Jane's Conference.
HTML5 Wow Visualizer. Shown at Google I/O 2011 - demo courtesy of Eric Bidelman and Arne Roomann-Kurrik.
GAL 9000 Shown at Google I/O 2011 - demo courtesy of Eric Bidelman and Arne Roomann-Kurrik.
b.uild.in/synth Another cool drum-machine based application - demo courtesy of Rob Stenson.
Stories in Flight Visualizer courtesy of Thomas Sturm.
Technocrat is a fun interactive ambient techno machine courtesy of Joe Turner - more info here.
Orbisyn is a custom synthesizer with programmable rhthymic modulations by Jussi Kalliokoski.
A Compás is a flamenco metronome web application.
X Sound is Multi Sound Application that uses XSound.js (Web Audio API Library).