Who doesn't like free gifts?

Giving away something free without asking - a random act of kindness - is an established loyalty generating tactic, especially in retail businesses.

The "growth hacker" approach to this would be to:

• Identify dis-engaged users (such as users who haven't logged in for X weeks)
• Offer a personalized discount or a free upgrade - just as a gesture of thanks

This creates a "surprise and delight" reaction, something even HBR calls the "most powerful marketing tool".

For example, HostelWorld gives out its least engaged users discount coupons as a gesture of thanks. To further the impact, it personalizes the discount coupon message ("Hey Joshua") and hints at its use ("for your next trip").