Looking for tool/software to create HDR photos on OSX
Photomatix Pro is available for Mac.
Overall, it's the best HDR tool I've used. The UI is somewhat complex, but not obtuse. The results are consistently impressive.

Another app that I've seen used (but not used personally) is Nik Software's HDR Efex Pro.
This is a powerful app that seems to produce some very nice images.

Both of these are paid apps with free trials.