Lighting for xtracycle hooptie
If you go to any reasonably well stocked bike shop (or the bike department of a large department store) they will have a fair assortment of bike lights and reflectors.  In particular there are a lot of different battery-powered LED flashers available:



Mounting the light/reflector sometimes requires a bit of ingenuity, but you can often do pretty well using a cable clamp from a hardware store to attach to a rack or seat stay (if the light doesn't come with something suitable):