For me it's mostly food, right now. However, I also put some stuff there which I probably will never use, but not inclined to sell straight away. Soul coins, the last Nautiloid tank (which I acquired before the latest hotfix), Shadowheart's chain shirt, gloves of Absolute...
Yeah, for hoarding I suppose.
The problem is, it's the only reliably accessible camp storage container, which is available at any camp site (afaik). If we would have 2 or 3 such chests, sorting stuff between them would make sense (even if always lands into one of them when you use "Send To Camp" option). The way it is now, however, this single chest just turns into a huge pigsty.
