Ok on the first day of the minecraft 1.0 release for XBOX I downloaded the festive skin pack and used Scrooge as the skin. So I used the skin to give me an idea on a seed. So I put in a seed called "Ebenezer Scrooge" and if there was anything good I could use it again. Now there's really only one thing that stands out and that is that the coordernants X:-80,Y:63,Z:154 there's a mushroom biome very small though about like an island. So if you like mushroom biomes this is definitly check this out I hope it works for you and have a Merry Christmas!
Please keep all seed-related discussion to this thread. http://www.minecraftforum.net/topic/1531062-182-mcxbla-seeds-list/