The Woolong (symbol: ₩) is the standard unit of currency in the Cowboy Bebop universe. Woolongs are rarely traded in physical form such as in banknotes and coins; it seems that the 2071's economy is based on digital cash.
It appears to be greatly devalued to today's standards. For example, in Mushroom Samba, a single watermelon costs a thousand woolongs.
The Woolong has been adopted as a currency by bitcoin-based Twitter tipping service, BTCTip. One Woolong is equivalent to one millibit or 0.001 Bitcoin, which is worth $0.01 at January 4 2013 exchange rates.
The Woolong has additionally resurfaced as the currency used in Space Dandy, which features many of the staff from Cowboy Bebop.