So Sci-Fi and comedy appear to be the most popular choices.
I'm away for the next 2 weeks, so you'll all have to carry on without me

After coming up with the basic storyline, you can start to beef it out with a timeline of events, add in plot twists etc. Then it's on to writing the script itself. Remember it's a team contribution, and you can use this thread to discuss any queries or aspect of the script, and even post sections as you write them.
Have fun!