The document discusses 5 potential use cases for Heroku in a Salesforce context:
1. Cloud service mashup to integrate various independent cloud services like Salesforce API, shopping sites, and analytics tools.
2. Building a customer multi-channel app to interact with customers across different channels like SMS, voice, email, social media.
3. Creating a company portal to publish and manage company data and business logic defined in Salesforce.
4. Implementing a big data strategy using Heroku to store large amounts of customer, transaction, and competitor data.
5. Extending social media platforms like Facebook by creating custom apps to better understand customer profiles.