App for eye-friendly eBook reading on iMac or MacBook? Is there any program that allows a user to read eBooks or PDFs in a way that does not bother the eyes, pretty much like what Kindle does? Maybe by reducing the illumination of the monitor and using some other tricks?
What you are asking is impossible, I'm afraid. The Kindle uses a different type of technology for its screen called "e-ink" or electronic paper:

http://en.wikipedia.org/wiki/Electronic_paper

whereas laptops (and iPhones, iPads) have backlit LCD screens.

The essential difference is that the Kindle screen is lit by the light reflected off it - the same as a printed page - this makes it more relaxing on your eye to read.

There is no software way of achieving this on a Mac - you'd need an entirely new screen!

There have been rumours that Apple own some e-ink patents but nothing has come of this so far.