This is a really useful article; thanks I'd not tried EXIFInfo or TinyThumb and will have to give them a go now.
Personally I've been using ThumbCat for a while now to organise photos. Although there are one or two glitches with it, I find it's an excellent tool as an image database and gets better all the time.
The thing is, whilst I suspect on other platforms it would be expected that you'd use an external application to organise your photos, it's not really the RISC OS way to use anything other than the filer
One downside to ThumbCat is that you don't get a great deal of control over the HTML output, which I think is where Pic_Index and WebGen2 excel.