Another idea - how about making this concept the official 2015 GB? Working frame is a calendar week, and the result is to reflect "something" that fits into a matching real world time frame, e. g. a whiffy D-Day model in/for the week of the 6th of June? That does not exclude fictional time, e. g. stardate for Trekkies... just an idea, but probably too abstract?
I like Dizzy's idea, and hanker for a return of real group builds. A week is likely too short for most, but appreciate the idea of getting timed builds back on the forum. Heck 90 days was too short for many group builds.
I do like dizzys idea for a focus on a date of history, and gives you some time to think about what kits you want to abuse.
Ideas, not to celebrate war, but to hone in on a theme:
April 1st- bad idea/silly concepts
June- D-Day
November- Armistace, trench warfare/western front
May- VE day, or did the war go on?
May- spring cleaning- build the oldest kit in your stash. Extra points for really poor/old kits.
August- Atomic ideas
December- winter sets in (let it snow GB, one of WHIF's best GB's)