One of the nicest things about the arch version control system is that you don't need any sort of special daemon for it; the client manipulates repositories ("archives") over any filesystem-like protocol. This means that an arch archive can be stored on a WebDAV or FTP server, or accessed via ssh using sftp.
While CVS requires a bit more from its repositories for commit access -- locking, the ability to run scripts if configured -- it might be possible to have similar behaviour for read-only CVS access, meaning that a CVS repository could just be made accessible via FTP to permit anonymous checkouts.
It might be easiest to do this by writing a custom read-only CVS client; cvsup takes a similar approach for rapidly synchronising CVS repositories.