Did you ever thought about selling one of your hardware creations? Maybe some gadgets built on Arduino, Raspberry Pi, 3D printed artefacts as well as specific shields, boards, sensors or complete kits.
Emile Petrone founded a marketplace, tindie.com, where makers and hardware creators can offer their creations. There are already some really interesting creations on tindie, such as an Angry Birds-playing robot, MicroFTX USB-Serial Breakout or a Netduino Go! Relay Module.