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 economy is based on digital cash.
The Woolong appears to be roughly at parity with the mid-1990s Japanese Yen, or slightly inflated. The latter might not be the case if we consider the probable increased cost of consumer goods in a spacefaring society. For instance, a watermelon in "Mushroom Samba" was ₩1000. Whereas in "My Funny Valentine", we see debts such as ₩30M for a house, and ₩7000 for pizza. In "Stray Dog Strut", however the pet shop worker said that Ein could probably sell for only ₩2; this is probably an exaggeration, however.
If we assume the Woolong is at parity with the 1998 Japanese Yen, then conversion may be performed rather easily. A good rule of thumb would be to assume ₩1 is worth about 1¢ US, ½p, or a little less than €0.01.
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.