I will use xv to the day I die.
Great for remotely viewing / editing images (e.g. headless EC2 instances).
Has features I can't even find in a modern image editor.
http://www.trilon.com/xv/
It's unfortunate that modified copies "may not be distributed without prior consent of the author", killing any possibility of a "neoxv" fork.
Well, just look at what happened to xsnow. I installed Slackware 15.0 and my config automatically starts xsnow. I wanted to see why it hasn't started, only to discover a configuration window under my xterm, without borders or titlebar.
My next reaction was: removepkg xsnow, fetch xsnow-1.42, xmkmf, make, make install.
It changes the colors to greyscale for my non-color laser printer, scales it perfectly to fit the 8.5x11" paper, and prints.
I remember in 1997 during the first Mars Pathfinder rover mission that NASA was basically doing a live screen sharing session from someone's desktop and they used "xv" to load the image. I was 27 but I grew up obsessed with space exploration. Well I still love it, but at the bottom it said "UNREGISTERED COPY" and people on Usenet were talking about how NASA didn't register their copy. I think they did later but I was just so excited to see xv on national television.