Pimp my IBC. They did indeed wall from the ugly buttress tree catching themselves on almost every branch but it's 'greenish' to reuse them, they store 3 and 4 times what the garden centre jobbies do and save you a fortune.
With the frame I'd imagine you could easily wrap them in the some cladding or somesort to make them a little prettier. If you check ebay and do a spot of Googling there are other industrial types of liquid containers that are very cheap, very big and possibly not as ugly.
These IBCs with the cage on a pallet do weigh about 70-80kg and are a about 1m square so they are brutes to move and transport.
http://www.smithsofthedean.co.uk/IBCs & Baffled Tanks.htm
Rem that the tap is located very low making it quite tricky to fill a watering can etc. They are best sat on a fame or plinth. Consider the weight of 1000L of water being approx 1000kg at 4C.