I am not sure if this has been mentioned before in this forum or not so I thought I give it a try and mention it.
I would like plex to have the feature to download subtitles for a particular video on the spot, something like what XBMC does.
Currently Plex's subtitles agens either don't download anything or download everything and get you banned from the subtitles website.
I prefer Plex over XMBC any day of the week but one feature from XMBC which I think would improve Plex is the ability of XBMC to download subtitles on the spot for the movie or episode you choose.
I always use subtitles so because looking for every subtitle on the web could be exhausting I open my videos with XBMC first and download the subtitles then use Plex to watch the movie with the subtitle.