Run gem server in background on OS X. save as FILE, then do "launchctl load FILE". Symlink FILE to /Library/LaunchDaemons to get it started automatically on restart

com.florianebeling.rubygems.server.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>Label</key>
  <string>com.florianebeling.rubygems.server</string>
  <key>ProgramArguments</key>
  <array>
    <string>/opt/local/bin/ruby</string>
    <string>/opt/local/bin/gem</string>
    <string>server</string>
  </array>
  <key>OnDemand</key>
  <false/>
  <key>RunAtLoad</key>
  <true/>
</dict>
</plist>