Open Source Linux Based POS Systems?

tha_mink asks: "I am currently working for a number of clients that have very similar needs for a cost-effective POS system that may be integrated online. (read : cheap if not free) These are all small business clients with small budgets and so I would like to suggest something Linux-based, with a nice GUI, and a database I can get at through the web (PostgreSQL would be great). I have searched for and read the past Slashdot articles on the subject only to find that they are old and out of date. I have also done numerous google searches only to find that there is not a clear leader. My clients don't really need things like payroll and purchasing but inventory control, accounting, and customer storage are important. So I ask: What systems are available to fulfill the needs of small business without breaking the bank and without requiring any software from Redmond?"