In Writer, you can create a Table of Contents, which is an automatically-generated list of any text with a Heading style.
I’d like to be able to do something similar, where I write a document and then can highlight sentences in that document and quickly give them a custom style or something, which makes them look different from surrounding text and also causes those sentences to show up in an automatically-generated table. I intend it to be used for “To do” items, so I can view in one place a list of all items scattered throughout the document, and I can remove the style from an item when it’s done.