Currency

Currency in the 31st century, at least originating from the USA, seems to still be dollars. Most notes look just like they are today, and each one of them has the face of an important individual on it. The $500 note has Al Gore (2ACV07), the $300 note has Richard Nixon's head (4ACV16), the $10 note has Benjamin Franklin (3ACV11, the $20 note has a Blob, probably H. G. Blob, saying it is "legal tender" (BBS), and the $5 note has Abraham Lincoln (ITWGY). The coins also seem to be similar to what they look like today.

$1000

 * Richard Nixon's head.

$500

 * Al Gore.

$300

 * Richard Nixon's head.

$20

 * A Blob, possibly H. G. Blob.

$10

 * Benjamin Franklin.

$5

 * Abraham Lincoln.

Production
During the writing for "A Fishful of Dollars", the writers considered other forms of currency than dollars, including "quadloos", "bux" and "jules". But they probably decided against it to simplify things.