DPP has pixel mapping of dust bunnies and it is free. You shoot a white sheet and record it. Then DPP adjusts it for free. The downsides are:
1) Then you have to introduce DPP into your workflow
2) Needs adjusting when new dust arrives or dust moves
Why not just clean it. I do it all the time and it takes 15 minutes, which is about the same amount of time, to set up either Cs4 or DPP.
I can't recommend a free software fix, but if you find yourself using Lightroom, you can remove it with the clone tool, make a preset out of that, then apply it to all the images.
until I get to cleaning the sensor the right way, I just made an action (clone and healing don't record, so I just took a small sample next to the offending dust, feathered, cut, paste, flatten). did a separate one for vertical and horizontal.
rudimentary fix for now and not 100% perfect, but speeds up workflow tremendously.
