I love OpenDNS and use it on my devices whenever I can to speed up DNS lookups. However, there's one situation (not its fault) where it consistently causes me grief.
Public hotspots such as those at Starbucks, hotels, or airports, often have annoying login pages that require you to agree to terms before you can access the internet. I don't know the exact details of how they work, but they seem to intercept traffic to all sites (such as google, yahoo, whatever) and redirect you to a local login server.
If I use the DHCP-specified DNS settings at the free hotspots, everything works fine. However, if my network interface is configured to use OpenDNS instead of the DHCP-specified dns servers, I never get redirect to the login page and I'm unable to use the internet until I remove the OpenDNS servers from my configuration. Presumably the same thing would happen with Google's public DNS servers as well, although I haven't verified this.
Is there a way to configure Mac OS X to allow me to use both the DHCP-provided DNS servers as well as the the OpenDNS ones (eg. prefer OpenDNS but fallback on DHCP settings if necessary)? Or is there some other way to get these public hotspots to cooperate better with OpenDNS?