I struggled with this question as well in the past on UniversityTutor.com. Here are a few common ones from other sites that I looked at. Maybe the right one w

I struggled with this question as well in the past on UniversityTutor.com. Here are a few common ones from other sites that I looked at. Maybe the right one will jump out. number of photos, highlighted listing (AutoTrader) storage space (Evernote) top listing in search results (Google) top listing in search results, larger listing/photo, more photos (Haystack.com) number of projects, ssl, storage (Basecamp) number of faxes sent (FaxZero.com) number of subscribers (Aweber.com) Pro Badge, storage, num photos (Flickr) receive messages but can't reply (Match.com) send messages to full inboxes, racy photos, other stuff (OkCupid) If you don't mind sharing the app we could probably come up with some other ideas too. If you literally just have a laundry list of features, then yeah maybe the best and most useful ones you give away free, and the ones power users will want you can make paid. That is the heart of the freemium model I think: a causal user who might find it useful once a month should be able to use it free, and spread the word for you. A power user who is logging in almost daily, or making money from it (for business), etc should be a paid user.