He educated me about the mod a bit before the end of our dungeon run, and I promptly ran out and downloaded the thing, unzipped it into my interface/addons folder, and logged in to see what all the fuss was about. Lo and behold, it added a set of small buttons to my interface that, when clicked, cast Remove Lesser Curse on one of my poor, curse-riddled allies. (Remember when Remove Lesser Curse was called that? I always wondered where all the greater curses were.) I was blown away. This was infinitely easier than the clunky default interface! I immediately logged out, started perusing addon sites for other useful mods, and never looked back. Now my interface has evolved so far beyond the default that it's probably only one or two modifications away from identifying mankind as a threat and ending us all in a fiery hellstorm.
What was your first addon, and what prompted you to download it? Or are you one of the spartan warriors who insist on playing mod-free, as the good lord intended?