I've yet to see a site that depends on JavaScript heavily and degrades well. I think in this case you're much better of making secondary interface in pure HTML,

I've yet to see a site that depends on JavaScript heavily and degrades well. I think in this case you're much better of making secondary interface in pure HTML, cf. GMail. You could also make some small JQuery (etc.) enhancements to this bare-metal platform. Having something that degrades from full whizbang to dumb terminal is really hard, kinda like getting a desktop application that is fully cross-platform. Sometimes it's better to just use a common backend for separate interfaces.