I had seen some incredible shots from inside an old asylum, they were so eerily atmospheric, and since upgrading my camera would probably lead to divorce proceedings, this was the only way I have found to achieve a similar effect. The aurora around the cabin is a little annoying, but for a first attempt I was quite pleased with the shot. Maybe there is another way to do this with the D3100 if someone could point me in the right direction please?
I'm assuming you're speaking of a lot of the great Urbex/Abandoned photos out there that have this rather flat, ethereal look to them. Those places tend to be so dark inside that a tripod and long exposures are truly necessary. I don't know how much HDR or exposure blending goes on in those places, but any time you have a camera on a tripod it's possible (and perhaps recommended) to shoot multiple exposures at different exposure values.
The rest of what gives you that effect is all about post processing. There are techniques they use to give you that feel, some of which are very similar to what you get in a lot of HDR/Tone Mapping programs. Having looked at a lot of it they do, in fact, do a lot of bracketing and exposure blending - whether or not they do it in an HDR-specific program or purely in Photoshop varies with the photographer. Suffice it to say, if they're showing you windows
and room details then it's some form of HDR. It's also possible/probable that they're bringing in artificial lighting.
Here's a link to Pt. 1 of a 2 part walkthru of one person doing an urbex-type shot. 9 shot HDR.