I have always wondered how I could keep reading a lot of newsgroups that I care about without getting overwhelmed.
I finally found the answer, and it's adaptive scoring. Basically, articles are scored based on your reading habits and therefore some are deleted automatically, others are highlighted, etc.
It seems that Gnus does that out of the box. I have always contemplated switching to gnus, but have always found the bar too high. Maybe one day, when somebody writes a "slrn to Gnus for dummies".