UIAngband
UIAngband was an Angband variant, though not in the conventional sense; it contained no gameplay changes, but focused entirely on the game interface. It was never released, and never will be. On the other hand, some of the ideas contained within are worth preserving, which is why this page is still here.
Originally, I was planning to create another kind of monster recall, with less verbose English and a more stats-like display. Screenshots: one, two, three, and four.
I even got as far as altering the code enough to get flexible layout on-screen, as shown here. This layout is defined entirely in pref files, and the code is still around.
The other interesting thing added was the screen designer. This let you load and save screens, and then move around and edit them. It was pretty straightforward, and was used to create the monster recall mockups. (Now Vanilla has arrow key support, it could be made even easier to use.)