Meet the Microduino mCookie: small, stackable modules that are compatible with Arduino. They can be magnetically attached and programmed easily. You can use Scratch to program your modules using a drag & drop interface. What’s neat is these modules are LEGO compatible.
There are plenty of modules for you to choose from to complete all kinds of fun projects. This is also a fun solution for learning electronics. You can find out more on Kickstarter.