brompfication make specialized parts for modifying a brompton bicycle. i'm a huge fan of bromptons, no other folding bike comes close in terms of function and design. brompfication sell nicely machined components to customize them, and they look great.
what started as a small range has grown to include replacement hinge clamps, wheels, quick release skewers, frame clips and a new titanium seatpost. all the designs have a nice, minimal style, and many are made from super-light titanium.