As cphoenix said, I'll be cosplaying Nereid. ^^
Was originally gonna be Coatlicue (healing/bubble summon girl from Lost Age), but the wig for it was too damn expensive.
I've seen someone cosplay a Megaera (the girl in the blue dress with the two swords and angel wings) at Otakon 04 and Jia Crens cosplayed as Jenna and LimeBarb did a Mia.
Cyankirby did an Alex, too.
But yes, its sad that there haven't been a lot of cosplays from a game with such great looking costumes.
Doing a summon costume is quite a challenge, if you ask me, since the pics of them that can be found are very small and face one way, so you can't see all the details (which is one reason why I think the game would be even more gorgeous for Gamecube or some other non-GBA platform).
I wanna make some Djinn plushies X3
If anyone thinks they can pull a GS costume for Otakon, please let us know! It'd be great to have a photoshoot/group