Where to Buy
Available in the USA on Amazon.com here.
If you live in the UK, or mainland Europe, then you can buy from your local Amazon using this link.
A bright RGB (Red, Green, Blue) LED with built-in resistors and female header leads that can just plug directly into the GPIO pins of a Raspberry Pi. You can also find a Python library that makes the Raspberry Squid super-easy to use at: https://github.com/simonmonk/squid
When you buy a Raspberry Squid, you also get a neat box to keep it in together with Raspberry Leaf (pin identifiers) for both the old-style 26 pin GPIO headers and the 40 pin variety.