These are two circuits that sound great and are relatively simple to build. It's fun to play with layout/container, switches and pots.
Here's where I found the original schematic for the cracklebox. Starve pots are highly recommended. I'd also recommend this album by Michel Waisvisz, inventor of the cracklebox, made only with "cracklesynths".
The pipsqueak is from Martin Freeman and is a spiritual successor to the cracklebox--a digital noise box made with more readily available components (I bought some knockoff ICs for the crackleboxes). Here is the circuit, and here is the forum thread I found it on.