Minecraft server lists allow you to list your Minecraft server to be seen by others publicly! Most Minecraft server list websites also include a voting system that can be hooked into the NuVotifier/Votifier Bukkit plugin on your Minecraft server to give Minecraft players rewards for voting.
Some Minecraft server listing sites include a bumping feature. This bumps your Minecraft server to the top of the recently updated Minecraft servers list. On PlanetMinecraft for example, you can bump your Minecraft server by editing it.
As mentioned above, Bukkit Votifier is a fantastic way to promote voting on your Minecraft server and improve your Minecraft server's ratings on server vote sites.
Social Media is the absolute best for keeping your Minecraft community up-to-date on new changes, events, and so much more, while a community area such as a Discord server is fantastic for giving your Minecraft community a place where they can communicate with you and others who also play and enjoy your Minecraft server.
This helps in collecting Minecraft community feedback, hosting fun events like Minecraft building contests, and even just playing with your Minecraft community!