Im really gutted I missed the transformer comp, never mind.

I like really open ended challanges like the one currently running as people ideas can be far more out there, but there is the danger of the challanges being more like cg talks (eg "the jurney begins") were the entryies just dont seem to match the challage. so I think a mix of the both would work well.

something like "model yourself in your perfect job" - leaves it to your imagionation as well as
charator modling/texturing/lighting skills.

or lets mix it up abit like

1) charactor with weapon/vecheal
2) character and matching environment/landscape
3) animation of a character and matching environment/landscape

No matter what I`ll think I`ll have to do the next challage as this current one has been great fun and good pratise.