Jang Geun Suk has some nice songs and he is a very popular actor. You would probably like 'Mary stayed out all night', where he portrait a guitarist of an indie band, or the movie 'Do Re Mi Fa So La Ti Do'.
No Min Woo is more devoted to dramas than music, but he plays the role of a k-pop idol in the recent drama 'Full House Take 2'.
Kim Jae Joong (Hero) has also interpreted many dramas. Check out 'Vacation', 'Dangerous love' and 'Unforgettable Love' where he interpreter himself along with other members of his band TVXQ. From dramas with other roles not related to his musician career, I recommend the korean drama 'Protect the Boss' and the Japanese one 'Sunao ni Narenakute'.