Linux Point Of Sale Software & Equipment 
Touchscreen POS for restaurants and food and beverage organizations. Point Of Sale for resale for Linux and BSD.
http://www.viewtouch.com/poshome.htmlDNA Lounge: Source Code: Point-of-Sale
Point-of-Sale demo code at DNA Lounge.
http://www.dnalounge.com/backstage/src/pos/
gShop
The gShop Project is an OpenSource Project to create a fully-featured retail point of sale application, suitable for a range of businesses.
http://gshop.sourceforge.net/
easyPOS;
easyPOS is a GPL cash register written in C using GTK+.
http://easypos.sourceforge.net/
Free Linux Point of Sale
A complete point of sale system including a dedicated back office server, and web based administration interfaces.
http://www.bananahead.com/
Linux Canada Inc
Offer a point of sale application called 'Quasar'.
http://www.linuxcanada.com/pos.shtml
