Not a webcomic as such, but a thread on the Something Awful forums where someone is asking for comments on their ongoing comic "Jaybird". The story mightn't sound like much (a baby bird looking after it's bedridden mother in a big house shut off from the outside world) but it's really atmospheric and the art is incredible.
http://forums.somethingawful.com/showthread.php?threadid=3424156&userid=0&perpage=40&pagenumber=1 (Caution for language in comments).
http://forums.somethingawful.com/showthread.php?threadid=3424156&userid=0&perpage=40&pagenumber=1 (Caution for language in comments).