InsightSquared - #1 for Salesforce.com Pipeline forecasting, profitability analysis, activity tracking: all the small business intelligence you need. Works using CRM data and automatic syncing.
Outlook4Gmail - Outlook4Gmail provides easy synchronization of your Outlook and Google accounts
Aviso - Aviso provides predictive analytics software to help sales organizations optimize their performance and exceed revenue goals using machine learning algorithms and portfolio management techniques.
Boomerang for Outlook - Boomerang for Outlook offers email productivity tools to track, schedule and send mails at the right time.
Sidekick by Hubspot - Customer insight integrated with your email tools.
BlueMail - BlueMail is an email management app for Android, iOS, and Windows.