Discover the Hotspot-Specific Firmware Replacement: CoovaAP
If you have a supported wireless router, you can turn it into a hotspot gateway by uploading the free CoovaAP firmware to it. It offers easy hotspot configuration with a built-in captive portal so you can require login, show a disclaimer or usage agreement, and/or require payment.
It also offers bandwidth controls so you can control how much Internet power guests use. Plus you can use their free or paid hosted network management services.