Although they do serve to unify hardware design, there seems to be quite a bit of distaste for the software buttons in Ice Cream Sandwich when used on a smartphone. Even though I didn't really mind them too much when I used the Galaxy Nexus, there is a very valid argument to be made that they waste valuable screen space which could be better utilized.
Fortunately, there's always the custom tweaks to fix problems like this. Coming this time from the forum at RootzWiki, user Zaphod-Beeblebrox (a reference to a character in one of my favorite books, the Hitchiker's Guide to the Galaxy) released the above video as a teaser for a feature he is working on for the Android Open Kang ROM.
It's not completely finished yet, but it already looks like a practical thing to have. The concept is fairly simple, and just allows you to use the space where the navigation buttons are as a dock for applications, adding to the standard controls or even replacing some of them. Still, even a simple feature requires work to implement, and these kind of little tweaks are what stack together to make great custom ROMs.
The tweak hasn't been released quite yet, and will come to the AOKP ROMs first. It should make its way into Cyanogenmod 9 soon after.