I am sick and tired of people jumping on my boat without authorization and shooting it, and i am sure that many others are as well.
Once, I went to a flood server that had this system that if you went on someones boat without their permission, you lost 25 HP and flew off the boat. Each user had a interface in the Q menu for allowing disallowing users. You could allow them on by ticking their tickbox, and their where also options for allowing them to build with your props, allowing people to collaborate and make large boats. I am not sure if it was a different game mode altogether, a plugin or what, but it sure was good at controlling minges. The effects of it would disappear after 30 seconds of round time, so you could jump on othe rpeoples boats when yours died.
As for weapons, I find it a rather simple request. Simply make more weapons for the flood server! You could mix it up with some TF2 weapons, such as the minigun, pipe bomb launcher, jarate or add in more CSS and HL2 weapons. Either way, it could not possibly be a bad addition, everyone would welcome it.