I don't know if this could be done easily, but I would love this. I have my Transmission web UI accessible from the internet, and of course, I have a username and password configured.
It would be pretty sweet if Transmission could determine if the requester was on a local IP, and not require a username and password. (I access the WebUI a lot from my phone/iPad, and it doesn't save the http-level passwords). I feel like I have seen other apps do this, but can't say for sure.
Thanks!