Wireless solutions with multiple keys

[Nick Duda <nduda () VistaPrint com>]

Does anyone know any good products that allow multiple keys (wep/wpa/wpa2) for a single SSID that can be generated 
dynamically? I think I've seen hotels and such that offer something like this.

Example: A local corporate network that serves 500 people. This network has servers and all kinds of stuff. I want to 
add a wireless network using WEP (I know I know, WEP.just using as example). This wifi network has no connectivity to 
the local corporate network, rather it connects to a dedicated DSL line. If you are on this wifi network, you are only 
on the internet. These 500 people have laptops that can only be used on this wifi network.  I don't want to share 1 WEP 
key with 500 people. I want a way, a solution that these 500 people can hit up a webpage or something that will 
dynamically generate a WEP key for them. This WEP key should be able to expire. This solution can live on the local lan 
if needed.

- Nick