Chests made of a materials other than wood would be cool.
fireproof, looks good in brick houses
fireproof, looks good in sand structures
fireproof, slightly increased resistance to explosions etc
looks sleek and awesome, fireproof, explosion resistant
fireproof, very susceptible to explosions, looks awesome and expensive
looks fancy and opulent, is fireproof
There, thats 6 new chests. all of them are fireproof by virtue of the materials they are made of. only the obsidian chest is really explosionproof. the sandstone / brick chests just for use in sandstone, sand, or brick structures. The obsidian and iron chests would offer increased durability and resistance to explosions. The gold and diamond chests would be for treasure rooms and basically just look cool. they would all hold the same amount of items.
Also, since item theft on smp is often a problem, perhaps there should be some non-mod way to lock chests. maybe you could take a chest (of any type) and combine it with some redstone dusts to make a locked chest, like so:
I think the brick one would be more of a fireplace. Though I do agree that we need a metal / stone chest that is more secure in its contents, Also a stone chest would be very easy to hide in your house. :3
Maybe have the iron chest open forward like a safe?
I'm not sure about the other chests though. Maybe combine a chest with a gold block or diamond block or obsidian, but I don't currently know any very good use for more than 3 chests other than maybe making ones like obsidian the size of a double when it is a single chest.