I'm pretty sure that someone has mentioned this idea already, but I do sometimes wish that there was a way to give or trade items between players.
I'm thinking that such a system could be abused, however, so maybe there needs to be a maximum of items that we can give another player in a certain time period, and that some items that you need to find to complete a level for could be restricted from trade.
Items that would be useful to trade would be stuff you have to grind for like petals, fur, feathers, plasma globes, venom, croc tears, snow cones, etc. Not stuff you make in crafting. Does that make any sense?