It could be some good UI to support a protocol handler to join network games.
A protocol handler could allow players to make links to a server directly from a website or social service and have players join through that. It would also make the browser at http://servers.openttd.org/ more accessible.

URI scheme

Example of what an OpenTTD server link could look like:
openttd://127.0.0.1:3981?version=1.9.3&password=asdf&join=4&companypassword=qwerty

Suggested parts:

• openttd: because a scheme name is required
• // because everyone else does it
• 127.0.0.1:3981 IP address (or hostname) and port
• ? make a HTTP-like query string
• version=1.9.3 could in the future allow having a meta-handler that selects between multiple installed versions of the game for the required one
• password= server password, leave out if not required (prompt user if server needs one or the provided is wrong)
• join= join a company (leave out to spectate)
• join=new create a new company on connect, if possible
• companypassword= password to join company, or to set on the new company created (spectate if provided password is wrong)

Implementation

Every OS has its own way of registering URI handlers, the installers/packaging would have to handle that.

The implementation in game would be a commandline parameter such as -U <uri>. The game should perhaps ask the player for confirmation before beginning to connect, so they don't accidentally connect to random servers.