Name that app!

Hi, Comrades,

I'm reviewing a bunch of old text files. To make the process less tedious,
I'd really like an app that shows a file list in a left-side window and has
a right-side window that displays the contents of whichever file in the left
is selected. Certainly there must be something like that out there, but
I'll be darned if I can find it. Any leads?

Don.