What you could do is add your server on Voting websites/Server listing. I wouldn't consider it as advertising but as just putting it on lists for people to see. If you are also running Bukkit or Spigot you could download the plugin Votifier and GAListener. Votifier counts and records the votes and GAL gives people rewards for voting. Votes could help get your server popular and growing. The links below are links to websites that you could put your server on. Its free of charge.
Plugins to record and give players rewards for their vote:
If you would like, Private message me to get my Skype and ill be glad to help you set the plugins and the websites up.