More fuzz!
This one is kinda obscure.
This one will let you build a clone of the Buzztone by Höfner (yes the company that does the whole Beatles-Violin-Bass-Thing)
Crank the Depth control and enjoy thick vintage fuzz.
Roll back the Depth control a little and be surprised how good it sounds as a overdrive.
Roll it back even more and use it as a good sounding dirty boost.
Or plug in your bass and be grateful about the low end that this pedals lets you keep.
You can also get this as a kit from Musiking here