I've noticed there have been requests to 'favourite' specific answers before. However, it'd be great if we could rename the title of posts we have favourited so that it's easier to find what we're looking for. Of course, the new name would be only visible to our account and wouldn't rename the actual post title.
Sometimes I favourite a thread, simply because there was a useful comment in that thread rather than the question or answer itself. When I'm looking for that comment, I have no idea which thread it's in and so it would be useful if I could rename the 'favourite' from the thread's title to my own description so that it's easy to remember why I favourited that thread and find what I'm looking for.
Edit - To clarify the reason for the alias. Say for example, a comment provides a link to an interesting article I'd like to read later. That article fits in the context of the thread, so I don't want to bookmark is separately in my browser. Six months down the line, and fifty more favourites added, I want to find that comment again. Using title aliases, I can just look for the favourite titled 'Article talking about XYZ'. Clicking that will take me to the original thread, with full context. Advantage of this method over attaching notes, depending on how the notes are implemented, is that you can immediately see the titles whilst scrolling. If I have to click on a button to see the notes attached to the favourite, that could take some time if I have hundreds of favourites.