What options are there for connecting peripherals to a micro controller?
We used 3.5mm phone jacks and scokets on the SenseBoard

The board used stereo jacks, because the cable carried power and ground as well as the sensor input. 

Some sockets have an extra circuits which is opened or closed when a plug is pushed in, so it is possible to detect something being plugged in or unplugged. That can improve the user experience by giving some feedback, or 'auto-detecting' changes.

They are easy to get hold of, and come in different heights and bezel mounts. They have a nice positive feel too.

Scott Seidman has pointed out, the jack touches more than the 'correct' connections as it is inserted and withdrawn. The socket might apply a reverse voltage to the plug as it is inserted or withdrawn.

I haven't got the schematic on hand, but I am 99.5% confident: power was on the tip of the jack, on the basis that it is furthest inside the socket, and the last part to connect. The sensor connection is input to the board, so no power there, and hence no issue being touched by an unpowered jack plug.  Ground was at the base of the jack, or the first connection of the socket. IIRC that was also easy to connect to the shield on shielded cable in the jack.