A recent hobby has been to build and install a solar panel on our roof. It's comprised of 36 common Evergreen Solar 3"x6" 1.8W cells in a simple wooden frame with a sheet of acrylic to protect them. My Dad helped run conduit and wires last weekend and the open source hardware/software available these days makes it unbelievably easy to setup a voltage logging apparatus. A 10k then a 2.2k resistor straddle the wires coming into our basement from the panel. The junction of those is connected to an analog input on an Arduino Mini.
This code draws a Mandelbrot pattern on the 132x132 Nokia 6100 type screen with Epson controller (will not work for the Phillips) from an Arduino. I started with the code example from this post and made some optimizations- especially to the serial communication code. Then I ported the Mandelbrot algorithm from here.
Here is a prototype two-axis pointing device designed to aim a laser diode's beam. It operates via USB to Arduino with my modified Firmata and AS3 Glue code and two EasyDriver stepper motor controller boards.
This design is movable over virtually the entire sphere but it's difficult to build a well-aligned bearing and gear or pulley system.