Things you might want to consider:
- Install "anything to anything" connectivity between Sitecore and Salesforce
- Add a login control to your Sitecore website and store the credentials in Salesforce
- Use Sitecore Web Forms for Marketers forms to create Salesforce leads and contacts
- Push Sitecore DMS data to Salesforce when new leads and contacts are created
- Extend Salesforce email capabilities by integrating with Sitecore ECM
