Mercurial & SSH Passwords
One would think that if you have your keys all set up so you can log into a remote machine using SSH without providing a password, Mercurial would be able to interact with a remote repository over SSH without asking for keys as well.
One would be wrong.
I'm not clued in yet with how it all works, but however Mercurial uses SSH, it won't apply your local identity against the remote authorized_keys, unless the ssh-agent has it. So, if you can log into a remote machine automatically just fine but Mercurial keeps asking for your password, run ssh-add. It'll add the default identity (id_rsa or id_dsa or whatever you generated) to the ssh-agent. Mercurial should now work without asking for a password.