hey!
I would say that this is a good idea! For some feed back:
1st, nerd created, as it could be sorta stealing almost.
2nd, I would say a whole word, judging by the feedback from the tree contest.
3rd, Yes, I would be interested in that, for planes, cars, etc.
4th, I would say a limit of 5 in every world, so people don't claim and/or do nothing in every plot.