I would be using it outdoors so you think it wouldn't be much point..?
Outside is just more difficult, because you obviously don't have a ceiling to bounce off. So you have to provide your own, much larger, light source.
If you just pop on a little Stofen-type diffuser cap, which usually works great indoors, you will get zero benefit. At the other extreme, I've got a big camera bracket which carries a 33in umbrella, and that gives fantastic light - almost a portable studio, I use it for chasing kids about - but it's extremely combersome and you look like a total goon! So pick something inbetween that suits the situation.
Short answer is to get one of these - Lumiquest Quik Bounce £40 (top left here)
http://www.lumiquest.com/products.htm which will go perfectly on your 430EXII. Lumiquest products are good, and free of bullcrap. The tutorials on their site are also good, explaining how flash light works as well as individual products - to the point, and brief
TBH, if you just want some softer light outside, then the Lumiquest UltraSoft or BigBounce are perfect, but I suggest the Quick Bounce because it is almost as good for that, and far more versatile for loads of other things - softer direct flash, softer fill-in, bounce-fill with variable ratios, horizontal or vertical framing, efficient and doesn't waste half the light out of the back, fast to use, folds flat. I have loads of these diffuser things and the one I almost always end up using in unpredictable social situations is the Quik Bounce, because it can turn its hand to so many things indoors and out, and do a pretty good job of most of them. Bear in mind though that the size of the light, ie the softness, is relative to distance so you need to keep close to the subject for maximum benefit. Over 3m or so, the benefit over direct flash is almost lost.
This area is very ripe for DIY. Have a fiddle around with a simple bounce card for nothing
www.abetterbouncecard.com or a plastic milk bottle works well. Very well actually - try this. Get a 2L plastic bottle and cut the top so it fits over the 430EXII, pointing straight up. You now have a Fong LightSphere-alike, but better because it's bigger. Try that indoors. To put more light on to the ceiling, cut off the top (ie the bottom) or make a simple hinge with a strip of bodge tape. For outside, cover the back, sides and top with kitchen foil so that just the front is left bare and you have a Lumiquest UltraSoft-alike. Works great
Some crazy ideas come up on google
http://www.google.co.uk/images?q=pl...&source=og&sa=N&hl=en&tab=wi&biw=1135&bih=514
The secret is understanding how light works, and getting a handle on this will transform your photography - no kidding! And this is all you really need to know:
a) The bigger the light source, the softer the light. And the source gets smaller with distance, relative to the subject.
b) The inverse square law says that when you double the flash to subject distance, the brightness of the light is reduced to
one quarter which is two stops. Flash exposure is very sensitive to distance.
c) The angle of incidence is equal to the angle of reflection. That is, light bounces off a surface at the same angle that it strikes it, like a snooker ball off the cushion.
Try the milk bottle - you'll be hooked
