I've had two Government report covers before, in the 1970s. The first was the Met Office annual report for the drought of 1976. There were barriers erected over the dried-up bed of Ladybower Resevoir, cracked mud like a desert, with large warnings not to venture on to the mud (it was a thin crust over several feet of slurry). So I did, I took a 17mm lens and crawled out over the first few feet, and did a wide-angle view with the dramatic cracked mud pattern. I got very muddy shoes and knees/arms but did not get sucked in, and it made big uses in the national papers, then got bought for the Met Report cover later.
I also had one for the annual report of the Dept of Employment around 1975, a snap of two schoolkids with sort of typical 1970s slouched shoulders and flared trousers, seen from behind, unidentifiable, walking past a polished brass Department of Employment sign and a closed door (now they are all 'shops' with big JOBCENTRE branding - not as classy!). These days most photo libraries would reject the image a) no model release b) subjects under 18 therefor I must be a paedophile and should be arrested immediately c) no property release.
Alamy is a fortunate exception, you can simply state no model release, no property release, and they let the client shoulder the responsibility for use. Same goes for my UK BORDER shot, lots of people in it, no model releases. But I'm very careful when shooting to avoid directly identifying people when hunting down shots with editorial stock potential. I shoot a lot of pix from behind, silhouettes, details. Here's an example from last week - one frame, one chance, no question of motordrive firing or chasing the subject - just react very quickly and grab:

Slightly cropped from Alpha 900 28-105mm shot. Dead sharp, fortunately, where it matters on the fabrics. This one will go into Alamy unreleased - suitable for editorial uses. It's not as straight as it looks, logos have been retouched from the insoles and straps of the sandals. Selling points: almost perfect subject - right age, weight, skin colour; couple happened to have chosen co-ordinating colours for their clothing, all of it beautifully clean; no logos or labels visible on clothing; both holding their sandals; good diffused light matching the pastel colours. Finally it's a real shot, not some posed beach model scene, and far preferred by mags and newspapers now to press release type staged pictures. It is probably timeless enough to sell for another decade, and it's a really good quality 22 megapixel crop.
This is how we pay for our travel. This morning, another sale, this time from the Sony Alpha 900 launch in Edinburgh - one of my pix of the Red Hot Chilli Pipers cabaret show got bought. The money is never very much, it is unpredictable and it would be extremely hard to make a living shooting stock 'on the hoof' (I know two or three who do so and they work VERY hard, filing hundreds of shots every week). But it's also a kind of game, it gives you a focus. Some people hunt wildlife or play golf, we chase images. And while like any other photographers, we love to find truly spectacular ones (great landscapes etc) it's more fun when the type of image we hunt down can be found in all kinds of places, any kind of light.
Here's the night before we were flying to Mexico - Radisson SAS at Manchester airport, the beer (Boddingtons) is very regional to Manchester and almost iconic with the curved pint glass:
OK, it's private property (Radisson) but they will never care, and the beer has a logo - but in this case, the logo is vital. I've sold my photographs of pints of beer repeatedly through Alamy, a major Good Beer Guide sources lots of their pix that way every year. I've never sold a studio shot of beer - which is what all the regular stock shooters try to take - or an anonymous shot (which is all that iStockphoto, etc, will accept - no logos!). The beer guide and similar buyers want a real location, natural lighting, and a clear name on the glass.
It is the best excuse around for trying every new beer en route when travelling, I know they won't cost me anything if they come in the right glass, good condition, and a great background!
David