Point of Sale (POS) Application

[eluser]kurucu[/eluser]
Wow. Interesting project and plenty of controversy!

My thoughts:
- The hardware will interface with the client, not the server, so it's not a PHP problem but a Java/ActiveX/other problem... which makes it a lot easier as the program can run and interact with the user, then just call a server (PHP) request with the results
- Manual SKU entering sounds horrible - but then we have no idea of the size of shop or type of products. A specialist/organised shop might be OK with auto-suggest dropdowns. I worked in a McD where we entered all SKUs manually through navigating menus or typing the remembered SKU number. In a supermarket this would be dead in the water.
- Security. Availability. Reliability. It had better all be over HTTPS, and have the highest availability rates going. I'm not giving any webPOS my credit card knowing it's being transfered via an insecure AJAX request.

Personally, I'd expect a project like this to be done in (you said rapid development) C#, VB, Mono, whatever. But that's the fun of the world! Surprise us with a web-based (, reliable, secure, easy to use, scaleable) POS system!