After reading strobist.com (a fantastic source of info/inspiration for all things to do with off-camera flash), I was inspired to create some light modifiers.
The easiest to create are snoots/grids, so that's what I did. By a lucky coincidence, the easiest framework in which to create these bits of kit happen to be empty pringles tubes, so for the sake of research, I found myself having to consume two tubes. :-)
A full size tube was used as a Snoot, and a small tube, with the addition of some black drinking straws, for a Grid.
So, first have a look at a reference image (i.e. a pic of my wall) with the bare flash, with apologies for commiting the sin of using the flash on the hotshoe...
Nothing very interesting about it, but it shows the wide coverage of the flash without modifiers.
Next, the same shot, but with the Snoot added:
Notice the much tighter light pattern - the exposure of the candle is unchanged (and thankfully, has picked up no colour cast, as far as I can see). This is all about controlling spill onto the background.
Finally - with the Grid:
This is a FAR tighter beam, with far more defined edges and no spill. This was shot from about 6 feet from the wall (the candle stick is about 12" from top to bottom, so the beam is pretty much 1 foot @ 6 feet distance).
Great stuff - now if I could only find the off camera cord, I could try this without the horrid shadows....