Now that the entirety of Google's Android phone OS has finally been released under the Apache license, I have modified the Droid Sans Mono font so as to include a more easily distinguishable zero, for the benefit of my fellow programmers. I thought it was a great-looking font for the most part, but the vague distinction between 0 and O simply wasn't good for peering through long listings of program code.
(Despite the Ascender copyright notices contained within the font files, they are indeed now licensed under the Apache license; check out the Git repository if proof is necessary. I have left the Ascender copyright in the modified font file, in keeping with the appropriate sections of the Apache license.)
So here is the modified font, which I have named "Code Sans Mono Z". I had originally named it "Droid Sans Mono Z", but there were potential trademark issues with my using the Droid name, hence the change.