There are definitely plans in place for a favourite's system.
I wanted to do something dead simple, e.g. "Give it a star".
Then a message by each map would say "This map has been favourited 12 times". (for example).
rewolf31, if you really want, I could add a 'watch this map series' function that sends updates each time a new map is added. Like you suggest, this would be tied loosly into the favourites system. I'm not sure it'd get much use though (hence is it worth the effort?).
puke, I want to keep away from 1-5 ratings if possible. I really don't want to discourage new players from uploading their maps. If its just a simple 1 star favourites system, at least you (the visitor) can keep track of your favourite maps, and new visitors to the site can see popular maps, without implying/making anyone feel like they posted a 'bad' map.
At the moment I'm writing a "browse points of interest" page, similar to browse maps and browse comments.
Next I'll be reworking the map year numbering system, simplifying year to a four digit number and adding an extra field for "season".
This will allow / lead onto points of interest sharing across multiple fortresses in the same series.