Yet another couple of add-on boards, but these look very interesting.
The L293D board:
This is a DC Motor controller using the venerable L293D from ST (and others). The L293D is dual H-Bridge driver capable of driving 36V DC and 600mA per H-Bridge.
The MiniPiio Relay2 board:
A simple two relay DPCO board. Either of the relays can be selected from 8 off the GPIO pins from the Raspberry Pi expansion header.
There’s also an RS232 board and at least another one, but the site is done as a blog so it’s a little difficult to just see a list, let alone spot where to buy from.
Will edit this post later if I can find more info!