Google Contacts - Google Contacts is Google's contact management tool that is available in its free email service Gmail, as a standalone service, and as a part of Google's business-oriented suite of web apps Google Apps.
Microsoft Office Access - Access is now much more than a way to create desktop databases. It’s an easy-to-use tool for quickly creating browser-based database applications.
Free Address Book - In our contact management software you can store fast and easily name, phone numbers, birthdays, address, company name, city, mobile numbers, insurance and loan info, e-mail addresses.
My Visual Database - Using My Visual Database, you can create databases for invoicing, inventory, CRM, or any specific purpose.
Clearbit - Clearbit provides Business Intelligence APIs
MongoDB - MongoDB (from "humongous") is a scalable, high-performance NoSQL database.