When you write up a post (not an image, an actual blog post - http://thpstockphotos.com/500-royalty-free-stock-photos-online/ ) there is an option in the Post Editing screen for a Featured Image.

but this doesn't seem to show up anywhere when chosen? Any ideas?

Leo, is this something you can easily make display, in the blog page overview, and in the post itself? If so, perhaps will need an option not to have full sized image displayed if someone chooses a stock image for example it will show up huge. A nice little 150px or so thumb would be great.

Please let me know if I am missing something!

Easy implementation. Sometimes featured images can be a little invasive popping up where you don't want them. Please tell me where you want featured images to show up (in all practicality) and I'll work it in right away.

Very true. Another wordpress theme that I use has a little tick box in the post edit screen, something like "display featured image in post?" in case you don't want it showing up IN the post, but want it as a preview FOR the post. That might be a solution.

I'll send you a screen shot of where I reckon they would suit.