Here in the UK, Amateur Photographer ran a Christmas article with some DIY projects in it including a ring flash made from a plate cover. Copyright no doubt prevents me from posting the article itself, but when I start mine I'll document it and post here. Ideally I think you need an autofocus camera, whatever one of those is, but I'm making mine for my Nikon F3 as I can use the Speedlite to hold it up (I think - this may change when I see how much it weighs!) and allow me to get to the lens still to focus. Failing that, there's always focus-by-foot...
Oh, and I also made a flash diffuser from a milk bottle and a box that a mini Christmas pudding came in. Works - but the bokeh keeps coming out holly-shaped!
Adrian