What makes freemium pricing work?

photo by http://www.flickr.com/photos/bstabler/   Should you give away your product for free? The concept of “freemium” — or providing a product offering that doesn’t cost the customer anything, and allows for the prospect of future upsell — has great success for products like Mailchimp, Dropbox, Evernote, and WordPress. The basic idea is that some number…