[ATDrake]

Depends on the book.

Most often for short story collections/anthologies. I highlight the chapter title in the TOC to indicate which ones I've read.

Also occasionally for omnibuses, so I can keep track of where I am in which book in the omnibus if I decide to abandon one early, sometimes using the same title-highlighting trick to indicate what/how far I've already read so I can clean up any place-holder bookmarks that might otherwise confuse me on where I really left off.

Non-fiction is also a firm yes, for much the same reasons. Admittedly I don't own much in e-book format, but I do extensively use the TOC when available and decently-fleshed-out to navigate all the ones I've tried.

For single volume novels, which are probably the thing you're really talking about, it depends. For many novels with a straightforward linear narrative, it's something I'd appreciate seeing if the chapters are indeed titled anything more fancy than "Chapter 1; Chapter 2". It does help keep track of the story, IMHO, if you go from "Entering the Fearsome Forest of Fire" to "Interlude Back at the Palace" and you can more easily skip ahead to the good parts upon the re-read.

And for something like George R.R. Martin's A Song of Ice and Fire series which has a bunch of alternating viewpoint characters who each get chapters titled with the POV name, I'd consider it fairly essential to include those in a TOC for future easy reference so I can flip back and forth between Character B's chapters if I decide I want to go back over their plotline in particular.