Here's a good circuit if you want to avoid those clunky and expensive 3PDT switches and use a soft-touch momentary SPDT footswitch insted, or something else, like a push button switch.

One could argue that this one isn't really suitable for vero (tons of links...) or worth the effort, but I think it's nice for those extra special builds and it's also much cheaper than using relays. It does take a bit of space, but it can fit in a 1590B (depending on the size of the effect circuit).

Another cool effect by Robert Penfold. I could not find any info on this one so I made a layout out of pure curiosity. I was expecting a ring mod, but it's actually a cool metallic sounding octave fuzz/distortion with a fairly strong octave up and a weird stutter/tremolo mode (!) depending on how the Bias pot is set.

The only problem with this circuit is that it uses a LM565 chip which is obsolete and can be hard to find/expensive. I didn't discover that until the layout was finished (doh..) so I had to pay around 10€ for five chips from ebay.

Note that the trimmer has a very small sweetspot for the effect to work at all.

Here's an interesting Fuzz by RA Penfold from the book Music Projects (1994)
Moosapotamus has a good article on why it's a bit different from the usual fuzz.

"The Mouthmeistor" by Tiny Dazzler Electronics, a cool fuzz/wah. Have a look at my completed build here. 

Here's one insane fuzz/noise machine invented by Anchovie at the diystompboxes forum (original thread here). Have a look at my completed build here.

Here's a nice little 1w solid state amp that will fit inside a really small enclosure.
I always wanted more clean sound/volume out of my noisy cricket and this is it. :)
Have a look at my completed build here.

The Carlin Compressor (aka Compressor/Fuzz) is a swedish cult classic built by Nils Olov Carlin in the 70's.Read the background to the compressor by the creator here. Have a look at my completed build here.

Note: It's important to set the trimmer just right, there is a small sweet spot - 
Set the pots to maximum sustain and minimum fuzz and adjust until it's not too noisy. 
Turn it up if you want more agressive compression/fuzz (at the expense of noise)

I noticed after doing this layout the moody sounds offers this one as a DIY kit or seperate PCB.
Check out moodysounds.se

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

Here's an early layout I forgot to post. It's the "bazz fuss" by Runoffgroove, modified with a LED for clipping and a tone control (Mark Hammer's SWTC). Super easy build and it sounds great for bass, and guitar aswell.

Soundclip:

Another Octave Down, very different from the Synthbox. Cleaner and bassier octave.
Modded by me for true bypass. Have a look at my completed build here.

This circuit is a bit below unity gain, but John Kallas did his own version of my layout with an added boost daughterboard. Check out his layout here.

Here's a layout for a very nice DIY octave down by Liquids (forum member @ diystompboxes) based on Joe Davisson's Shocktave. It's a very cool "synthy" sounding octavde down that tracks fairly well.

Here's a layout for the original Shocktave (not verified!)