Gallup.co.kr asked 4203 Korean people aged 13-59 nationwide in July, September, and November to find (among other stuff) the most popular idol in South Korea.
The report is here (gallup.co.kr link), and in the table below the results:
Kpopalypse
A blog by kpopalypse about k-pop related stuff.
AsianJunkie
Quality K-Pop journalism and satire site.
r/kpop
Great source of K-Pop news and stuff
MV_DATABASE
Comprehensive K-Pop MV Playlists
Selca Kastden
Female K-Pop Idols Instagram and Twitter aggregator
Daisuki - Korean Music
K-Pop MV Database with YouTube views and various stats