Peter Speer demos the Voice of Saturn sequencer, an inexpensive DIY sequencer kit.
He’s also got a review at his site.
Bottom line?
“In total, the Voice of Saturn Sequencer took me three nights to complete (about 12 hours altogether). If you have more experience in kit building than I do (which is to say “some”), I’m sure [...]

Aurora is an awesome open source usb powered multichannel mixer in a typical DJ form factor. Aurora is designed to easily integrate with your favorite midi compatible software.
The device features two linear channel faders, a single a/b crossfader and eight backlit buttons.T wenty four backlit knobs allow you to control effects.
Aurora, unlike most midi controllers, [...]

This video showcases the Thingamakit, a fun DIY project that lets you build your own anthropomorphic noise maker.
Comes with:

detailed instructions
fully labeled components
simply layed out circuit board with minimal hand wiring.
2 ready to blink LEDacles
control panel and face stickers

Bleep Labs has introduced the Thingamakit - a DIY project that lets you build your own anthropomorphic noise maker.
According to Bleep Labs, the Thingamakit features “all the sounds of Thingamagoop plus
triangle wave LEDacle with shape and speed control. Second photocell patchable to modulator and photocell rate. Square and Triangle wave output.
The satisfaction for making an [...]

Here’s something fun I saw highlighted at the Califaudio blog - the Theremug, a DIY project that turns your cup of coffee or tea into a theremin, of sorts.
Here’s Kyle McDonald’s explanation of the Theremug:
1 Prepare some tea
2 Expose the L/R leads on an 1/8″ cable
3 Immerse leads in tea
4 Plug cable into audio input
5 [...]

If you need any more proof that interesting synths can be made from just about anything, for very little money, check out the Sonic Picnic Set:
the sonic picnic set is a low tech modular system
connections are made as needed using crocodile clips
these pictures show some of the boxes
You gotta love this 4-joystick panner, too:

Check out [...]

This video demos a cheap dub siren, made from a circuit bent sound generating keychain.
Full instructions at GetLoFi.com.

This video demos the Tapehead Inspector - a sort of tangible sampler. 
Here’s the background on it, via Roy Mohan Shearer:
Inspired by the reversal of the name of a musical trio that I play in with Chris Croasdale and Mr. Jonnie Common. We’re really into tapes, and as Chris’ birthday was coming up Jonnie and I decided to make him [...]

This video demonstrates making a cheap multitouch control surface, the MTmini:
For this to work, all you need is a room with (at least) some light. The results will be best when the room lighting is even (no bright lights shinning from one direction onto the multitouch pad).
When you place you fingers on the surface, shadows are [...]

Instructables has a project that shows you how to make your own Daft Punk outfit:
As a lighted costume designer, I get a lot of questions from people who want to know how to make their own EL wire costumes (many of them seeking to mimic the immensely popular Daft Punk red robot suits, which I [...]

Here’s something different - Andrew Benson’s battery-powered wrist synth, aka the Whisper Synth:
Here’s another video of the whisper synth in action. I tweaked the circuit a little bit to make the sound a little louder, and am using a 9v battery now with a 7805 regulator to power it. The little lithium coin cells didn’t [...]

Remember the Beavis Board DIY effect pedal kit?
The OpenStomp Coyote-1 is a similarly open-ended effects processor, except that it’s for digital effects. 
Coyote-1 is an open source audio effects processor, built for guitar players. But there’s no law that says guitar players get to have all the fun!
With the Coyote-1, users can develop custom audio effects [...]

Division 6 is shipping Midify, a tiny board that can add a MIDI port to just about anything. 
It’s $35, and can be installed directly into a GBA, GBA-SP, DS or DS Lite, or with some extra parts you can interface it with other devices.
 
Features:

12 outputs
Outputs can be active-high or active-low
Map any MIDI note to any output
Mono [...]

The Internet has given circuit bending, the process of hands-on experimentation with battery-powered electronic noise making circuits, a life of its own. If you look hard enough, you’ll find that somebody, somewhere, has circuit bent just about any electrical toy or gadget that you can imagine.
Here are thirteen of the most bizarre examples of circuit [...]

Over at The Steampunk Workshop,  Jake von Slatt has a nice write up on a Jules Verne inspired analog synthesizer with etched brass control panels.
While we’ve seen hundreds of nice modular synths, you have to admit the etched brass panels on this are pretty sextacular.
Here’s what the synth’s creator has to say about [...]