For late night study sessions (or weekend movies) in front of the computer I wanted some light that lets me see the keyboard and provides some ambient lighting without it shining directly into my eyes. I solved this problem by mounting a 8W T5 fluorescent tube lamp facing backwards towards the wall onto the keyboard tray.
Ambient light build
The solution is not only simple and fast to implement but is also by far the cheapest and the components are readily available at any home improvement store. Using a LED would require a separate power supply and some form of light diffuser. A specific backlit keyboard would not provide ambient lighting.