Favorites
Allow users to keep a list of favorite listings.
Free 
Messages
Allow users to send private messages.
Free
Geolocation
Allow users to search listings by location.
Free
Reviews
Allow users to rate and review listings.
Free
Authentication
Allow users to sign in via third-party services.
Free
Claim Listings
Charge users for claiming listings.
Free
Paid Listings
Charge users for adding listings.
Free