In the topic about RAW images, I brought up HDRI as a reason to use RAW, but I think I need to expand a little on that: One thing I discovered recently and have been playing around with a little bit is to use HDRI techniques from a single RAW image. No doubt you have taken a photo where either the foreground had the correct exposure while the background was blown out or too dark or the other way around. For traditional HDRI, normally you would use autobracketed images to overlay them, but if you have a RAW image, you can derive the changes in exposure from the one RAW image at the cost of just a little noise if you don't use too high an ISO setting for your shots.

I use the tool I process my RAW images with, Adobe Camera RAW in my case, to change the exposure + or - 1 or 2 stops (EV) so it recovers the parts I am interested in and safe it off in a series of TIFF files remembering the EV correction I used (-2, -1, 0, for example). Then I run the TIFF files through an HDRI tool (like Picturenaut), tone map the result and safe it. Even without much experimenting, I already managed to improve shots I previously had discarded. Have a look here for a couple of my examples: http://hoshisato-travel.blogspot.com/search/label/HDRI