SQL Developer - Oracle SQL Developer is a free, development environment that simplifies the management of Oracle Database in both traditional and Cloud deployments.
Mongoku - A neat Web-based GUI for MongoDB
Toad Edge - Windows GUI for MySQL. SQL Syntax Check. Freeware (Basic Features) & Payware (Extended Features).
adminMongo - An open source admin user interface for your MongoDB
DbVisualizer - DbVisualizer is the universal database tool for developers, DBAs and analysts.
MongoLab - MongoLab is a fully managed MongoDB Database-as-a-Service platform that automates the operational aspects of running MongoDB in the cloud.