Does anyone know how to find out how many shares a company has on the market? The company I'm interested in is Napster, traded on the NASDAQ exchange (code ROXI) - I don't know too much about economics so I don't know if what I'm looking for has a special term?
Thanks in advance.

If the USA is anything like the UK then they should include this info in their annual accounts. In the UK these are submitted to Companies House and held on public record. The reports can be purchased for a nominal fee.

i dont think a company has a specific amount of shares to sell unless they are being sold exclusivly by the company to its employees. other than that the public can buy shares and that more people buy the more shares there are.