Here are few products that interest me.

An airline legal (62") case for Brompton that is less expensive and lighter than the B&W case.

A kit for replacing the Brompton chain set so it can accept standard chainwheels, i.e. for having lower GI.

A Brompton seatpost that does not slide (e.g. rough CNC machined part)

A GoPro adapter that fits on the Brompton mounting block

A water bottle mount that fits the Brompton (or the Vincero Design variation Brompton just announced)