Casino tokens and chips have been used for some time in gambling. Money is traded for the tokens upon entering the casino. The tokens are then won and lost in gambling establishments, and can then be traded back in for money (if you have any left).

Casino tokens are collected as a part of numismatics, more specifically as a specialized token collecting.

External Sites:

http://www.silver-state-treasures.com
http://www.ccgtcc.com/
http://www.chipguide.com