We have recently received a new product from MonksMakes (http://www.monkmakes.com/) called a Raspberry Squid.
These are RGB LEDs which have built-in current limiting resistors, and header sockets that will fit straight onto the GPIO pins of a Raspberry Pi. There is also a push button which, like the LED, has a built-in protection resistor and header sockets to fit straight onto the GPIO pins.
We think these are a brilliant idea, as for a quick maker project it saves all the usual fiddling around with breadboards or soldering. The image below shows how easy they are to use:
The Squids are also easy to use in terms of programming, as it is simply a matter of referencing the correct GPIO pins from whichever programming language to choose to make use of. The http://www.monkmakes.com/ website also contains a link to a Python library and some example Python programs that you can use with the Squids.
If you are feeling adventurous, there are also instructions for how to make your own Raspberry Squids.