I just stumbled over a nice use case for the webservice [1]
It would be quite nice to get a list of artists which are linked to a specific area. In this example a list of all artists from "Washington, D.C.". Ideally that would cover the "area" field as well as "begin area" and "end area". Like the list you get on the page of that area [2]

According to the documentation [3] you can't get such a list via the webservice yet. Neither via a lookup [4] nor a browse [5]. The only way I could achieve this was via the search server [6]. But that isn't really a nice and clean way to do so.

[1] https://twitter.com/MattBailey0/status/472056502501789696
[2] https://www.musicbrainz.org/area/af59135f-38b5-4ea4-b4e2-dd28c5f0bad7/artists
[3] https://musicbrainz.org/doc/Development/XML_Web_Service/Version_2
[4] http://musicbrainz.org/ws/2/area/af59135f-38b5-4ea4-b4e2-dd28c5f0bad7?inc=artists
[5] http://musicbrainz.org/ws/2/artist?area=af59135f-38b5-4ea4-b4e2-dd28c5f0bad7
[6] http://musicbrainz.org/ws/2/artist/?query=area:%22Washington,%20D.C.%22%20OR%20beginarea:%22Washington,%20D.C.%22%20OR%20endarea:%22Washington,%20D.C.%22