EDIT 2014-10-20
I added a soundclip. Notes: for this clip I had increased the 15K resistor (to the right of IC4) to 33K to lower the effect depth (I found it too wobbly), and I increased the 33K resistor to 47K to keep unity gain. This is as fast as this phaser goes, so it would probably be a good idea to mod the LFO secion aswell to increase the range. The wave-shape could also be better... but this is how it is without too much changes to the original schematic.

DIY phaser from ETI.

When I first built it up it was super noisy, so I modded it to reduce the voltage divider before the first phasing stage and I also reduced the makeup gain of the last transistor. Now it's totally usable, however a drawback of the mod is that there can be some minor distortion if you are using hot humbuckers.

It's important to set the Bias trimmer just right. It has a small area where phasing occurs and it controls the waveshape of the sweep aswell.

There are a couple of other things to notice.
When I drew up the layout I mistook the Bias pot for a Depth pot.. I don't wanna add the trimmer to the board, because it would mean even more cuts, links and possible a larger board (now it fits perfectly in a 1590BB). so, you will have to put the Bias trimmer on a separate small piece of vero.

The last thing is that it needs a 100K resistor from the output to ground, otherwise it will pop when switching to bypass (the original didn't have true bypass). It is easily soldered directly to the 3PDT switch.

EDIT 2014-10-20
I added a soundclip.

Here is a PT2399 based chorus by Distorque. I was a bit hesitant about this one because of the PT2399, but it sounds great. Very lush and deep. :) Original thread here.

If anyone wonders, depth lugs 1&2 are supposed to connect from two point on the board. It's not a typo :)

Here is another filter commonly found in hifi amplifiers that I adapted it for use with 9v single supply and guitar signal. In the middle of the tone pot it is almost completely flat and to one side it boost below the center frequency and to the other side it cuts. It also works great as a treble booster or a bass booster (depending on how you set the level), both as a stand alone unit or after a low output fuzz. :)

I recommend putting the level/gain pot outside the box insted of a trimmer in this one.

EDIT 2014-09-29
I added a PCB layout to the bottom of the post.

Here's a nice active Baxandall qualizer that I designed. Originally I did a layout for a schematic called "Bax in a box" (google it and you'll find it) that worked ok, but it was just "semi-active". The dual op-amp was just acting as a buffer and a make-up gainstage, so this is my take on an improved truly active version.

 You can put after your favourite fuzz or whatever, or just in a stand alone box.

EDIT 2014-10-20
Soundclip added.

Here is a cool sounding octave fuzz by Effdub Audio. A LM386 distorts the signal and a couple of transistors in a class AB push pull configuration creates the octave up (almost identical to Tim Escobedo's Push Me Pull You, except he uses a transistor front end).

It has a strong octave up and is very simple to build. :)

Here is a very cool optical filter/tremolo by Dead Astronaut. Built and verified today - works perfectly. :)