If someone asked me, "What's the most underrated feature in GNOME?", I'd undoubtedly show them this:
Did you see that?
All I had to do to extract that archive was right-click on it, and hit "Extract here". That's it. I didn't have to open an application and choose where I wanted to extract the archive to or anything. (It's probably the feature I miss the most when I use Windows or OS X...)
Oh yeah, and I forgot the coolest part: If the archive you're extracting contains a bunch of files that aren't grouped in a parent folder, it knows to create a new directory to throw them in (so you won't end up with files littered all over your desktop.) Neato.
What do you think is the most underrated feature in Linux, GNOME, or whatever desktop environment you use?