Current status: thanks, GNU Emacs and MH-E, for offering spelling correction for the URL in a message I'm reading that I'm trying to click on like GNU Emacs claimed I could. I can't even edit the buffer you're showing me the message in to do spelling changes on it, can't you engage something there?
I'm going to have to write a client/server URL opening system that runs over SSH, aren't I. Run the server locally, it SSHs to your remote session and starts the client, which listens for requests to open a URL, passes them to the server, and the server spawns appropriate local Firefox or whatever processes.
I can do this with X, but there are issues, including that Firefox increasingly wants to use D-Bus for remotely opening URLs, not X properties.
To clarify myself: I use SSH-forwarded remote X today, so today I can be on a remote system and feed URLs to my local Firefox via its remote control feature. It is just rather slow over my current DSL link, because it involves a bunch of round trips to manipulate X properties (and it requires a hacked Firefox that uses X-based remote control, which I have for now).
On Linux, Firefox's modern remote control normally uses D-Bus, making it intrinsically local-only AFAIK.
@lanodan Running Firefox on the remote server will either try to run an entire Firefox over SSH-forwarded X (guaranteed to be much worse than just the remote control protocol) or, at the best, try to do the same slow X property manipulation that I do with a little program[1].
(All browsers can remote control themselves locally, although the mechanism varies. Remote control through X properties works over forwarded X, but not remote control over eg D-Bus.)