Personalisation of your content, user interface and how your service interacts with users can improve your product dramatically.
Instead of sending every email to your users immediately, you can send lower priority emails only when it is day time, and continue to send transaction emails — such as orders — immediately. Services that send digest emails — a summary of activity — can send those near the end of the day.
E-commerce sites can check if they ship to the user’s location and inform users of rates accordingly.
You might show a different version of your web site with the appropriate language if it is already localized.
The nice thing about personalisation is there are lots of low hanging fruits and you can support personalisation progressively.
The simplest way to start supporting personalisation like this is to use a geolocation such as IP Sidekick to retrieve physical location information based on the user’s IP address.