I really like Kindle because it allows me to run my own selection of software on it. However, when I try to persuade other Kindle owners in all the benefits of running custom software, I usually get response like: but it already does everything I need. That might be true, but that's only because you never tried to read two column article on Kindle...
Fortunately, we have alternative pdf reader for Kindle based on muPDF library which is mostly written in lua. This is especially nice since it allowed me to add support for reading two-column pdf layouts which you can see in following video:
Basically, you press F to switch to new layout and then use fiveway buttons to move down the column, or right to move to top of next column, with page change if needed. If you move to left, you will be positioned to bottom of previous column which is useful if you want to read again last thing.
If you like this feature, liberate your kindle and download latest version of pdf reader, drop it in /mnt/us/customupdates and press Shift Shift I to install it from louchpad. Then press Shift P D to start it. Wiki pages of project describe all available shortcuts and there is active thread on mobileread forum.