From time to time I need to push some code from work, and I would like to be able to setup a my-work-ssh-keypair with write access to specified repo or two. I don't want to expose my main ssh key there, to limit possible access.

Would be great if I could do so, even if each such deploy-with-WRITE-key take one private collaborator slot. That would be superb feature. at this very moment I would need to setup new account, like myname_work and add it as private collaborator, thats kind of lame to just create more usernames just to do it.