I've come across an impressive piece of HDR software called FullDynamicRangeTools created by a German company. The address is[COLOR="Blue"]
http://www.fdrtools.com/. I spent a couple of hours playing with the Basic version, which is a free download, and was sufficiently impressed to buy the advanced version (about £45). The authors are a bit coy about the algorithms they use, but the results are impressive. The online help is adequate to get started, although some patience is needed to work through the notes given that they are an English translation from German.
One excellent feature is Project Management whereby you can set up, edit, and generally create HDR and tone-mapped images which you can store as a project. Thus, you can come back later and reload everything you have done so far. As far as I can gather you can set up as many projects as you like and they are then all available at start up - just choose which one to further develop.
There appears to be a function in the advanced version to combine HDR's, and the authors give an online example of a scene (a bottle of olive oil) taken under different directions for the light source. Each direction has its own HDR and then these are combined and tone-mapped. A fairly spectacular result shows the bottle appearing to hang in mid air without any shadows.
Although not yet implemented, the software is to be upgarded to give a variable depth of field algorithm to allow focus stacking. That would take HDR software into a new area.
I recommend those interested in HDR imaging to have a look.
David