I previously requested a feature for darcs. I always pull from an http repo, and push over SSH. I have to push using --no-set-default and typing the ssh repo in full, which I automate with a .bat file in each repo.
Today I noticed that darcs has _darcs/prefs/repos, which seems to list the repo's that darcs has used. In one of my typical repo files, I have an http entry and an SSH entry. To get darcs to behave the way I want, all I need to do is push using the first non-http repo in that list.
I have implemented my version of the darcs push command inside my paper tool, the code is all online here. Now I can delete all my push.bat scripts, and just type paper push from any darcs repo. As an added bonus, I now don't need to change to the root directory to perform a push.
It would be really nice if someone could incorporate this feature into the main darcs codebase. However, I'm quite happy using my paper tool for now. I certainly don't have time to patch, or even build darcs :-)