If you're more adept at playing with blocks than fiddling with a bunch of knobs and buttons, then you might need Mark Crosbie's SoundMachine. This sequencer lets you assemble a funky Midi beat using nothing but Lego -- and maybe a crude sense of rhythm.
The NXT-powered box connects to a PC and works as a scanner, making a panel covered in coloured 2x2 Lego pieces produce a specific beat sequence. Different colours trigger different sound effects, and custom software converts the brick-covered panel into a MIDI signal fed to Ableton Live which produces the final sequence.
It's no TR-808, that's for sure. But if you've got kids, you've probably already got everything you need to build your own.