Cool Atomo prototyping kits from HK.
"There are a number modules, including I/O boards, network expansion boards and even power supplies for bigger projects. For example, the project below has four I/O adapters and a power supply all connected to a Raspberry Pi. This means you can do some really interesting things with robotics and even hydroponics with the package the size of a hunk of cheese.
The kit costs $39 for early birds and should ship in June. You’ll be able to buy more packages and mix and match them as necessary."