This is pretty cute, it’s a captive portal for wifi access on the same lines as NoCat but intended for running on embedded Linux systems such as the WRT54G, and it’s called WiFiDog. Ahem. Anyway, their site says:

Existing captive portal solutions were either almost impossible to embed (NoCat, which relies on perl, GnuPG , OpenSSL ), or only designed to display disclaimers with no access control at all (NoCatSplash and others). Wifidog is designed to have optional centralized access control, full bandwidth accounting, node heartbeating and local content specific to each hotspot. It does not rely on a javascript window, so it works with any platform with a web browser, including PDAs and cellphones. It is developed in C to make it easy to include in embedded systems (It has been designed for the Linksys WRT54G, but runs on any recent Linux platform). A typical install only takes 30kb on i386, and a fully functionnal install could be made in under 10 kb if necessary.