Akatsuki no Yona (Yona of the Red Dawn) is an adventure shojo series which I am kind of in love with. Yes, it is shojo so it isn't very popular but I would love it if I could get a group together to cosplay from it!
You can read there series here: http://www.mangahere.com/manga/akatsuki_no_yona/
And I highly recommend doing so, it's a good story with great characters and character development as well as a real adventure storyline to it, not just 'OMGFIRSTLOVEANDSHIT'. (Not that I don't read a lot of those too. >_>; )
So far I have:
Hak (loosely, willing to change to someone else)
I'd love to have Yona, Jae-ha, Shin-ah, Kija, Zeno, and Hak being they are the main cast but Yoon, Soo-won, or anyone else from the series is more than welcome!
Here's a preview of what the series looks like: http://www.animu.ru/gallery/akatsuki...lpaper-001.jpg