Salesforce specializes in customer relationship management. It can easily scale to enterprise level, but is more expensive than other options.salesforce.com
The HubSpot free CRM is free and intuitive. They offer a startup program for discounted rates, if your needs marketing needs exceed their free tier.
Affinity is a relationship management platform that helps you leverage relationship intelligence to expand your network, support your portfolio, and increase proprietary deal flow.
Confluence is a collaboration wiki tool used to help teams to collaborate and share knowledge efficiently.