TiffHDR is a software for merging TIFF photos in order to produce an HDR picture, still in TIFF and uncompressed so that it may be further retouched.
Bear in mind that your photos are supposed to be aligned (use a tripod) and that this program does not provide any tool for correcting alignment.
It shall support 16 bit channels, but it is still in developpement; please come back in a few weeks.
After having tried hdrmerge and Luminance HDR, which both failed to merge my photos, I decided to program my own software. To be able to handle more than 8-bits per channel, and yet no go through the trouble of handling all the existing RAW formats, I chose to load TIFF files that may have been generated from RAW files with RawTherapee.