I have written a Greasemonkey script, which adds a table of contents to the OpenStreetMap diaries page and highlights new posts and comments. Advantage is being pointed to new comments without having to look into the post itself and to remember which comments you have already read.

Tested with Firefox (Greasemonkey), Chromium (Tampermonkey) and Opera (Tampermonkey, Violent monkey).

https://greasyfork.org/de/scripts/17297-osm-diaries-toc