Mercurial "server"

It might also simplify the administration to outsource it -- if you only have one repository and a couple of guys pushing/pulling it, you could do a lot worse than just hosting it somewhere like Bitbucket. (And for a one-repository solution it's actually free.)

Update: It is 2020 now and Bitbucket no longer supports mercurial, see: https://bitbucket.org/blog/sunsetting-mercurial-support-in-bitbucket

For a list of hosted or self hosted free or paid solutions see https://www.mercurial-scm.org/wiki/MercurialHosting

I believe reading the project's documentation is a nice start: https://www.mercurial-scm.org/wiki/PublishingRepositories.