What Is The Best HDR Software?
There are some great tools for the Photographer to utilize. I can name more than a dozen but lets focus on the main object. Getting the right look for an HDR photo.
You will need Ufraw to process RAW photos
You will need Luminance HDR and the Hugin plug-in to process HDR images
You will need Gimp for the final touches
Let me cover 3 things to be able to develop HDR photos
Setup or Pre-process:
Taking the photos is just the beginning to the end. You will need 3 or more photos of the same object, from the same distance with the same focus but with different exposures.
See this Tutorial for Pre-Process setup and recommendations
HDR Development:
This is where the magic starts to happen. Using 3, 5, 7, 9 or more photos you will have a deviation of exposures and will combined them using the software indicated. The Hugin plugin is used for straightening the edges and layering the images on top of each other.
See this Tutorial for HDR Development using Luminance
Post processing:
I like to use GIMP to manipulate the final image settings. This way the photographer gives the photo its final blessing.
See this Tutorial for Post Processing using GIMP
Look at Luminance HDR.
These notes might be useful.
It was called Qtpfsgui earlier.
And fotoxx (from the comments here) is also an Ubuntu package -- Looks promising, I'll try it too.
Macrofusion - maybe not best, but worth to try:
http://sourceforge.net/projects/macrofusion/
... and PPA:
https://launchpad.net/~dhor/+archive/myway
Disclaimer: I am the developer/maintainer of Macrofusion.