[Jtsummers]

If you select the timestamp of a comment (also when you reply to it) you can favorite it. This is much cleaner than leaving scattered "to find them later" comments around this site (in fact, I'm pretty sure it was added precisely to avoid those kinds of comments). You can also favorite submissions themselves. Favorites can be found in your profile.

[bckr]

you can click the timestamp and just keep the URL somewhere, like your browser's bookmarks

[exdsq]

Cool, didn’t know that! Cheers