Salesforce-Supported Tools and Software:
Force.com IDE Eclipse plugin for developing Force.com applications, providing source code editors, test execution tools, wizards, and integrated help.
Force.com Migration Tool A Java/ANT-based command line utility for scripted deployment of application metadata.
Community-Supported Tools (Salesforce.com Support Not Available)
Partner-Supported Data Loading Tools
Dataloader.io No download, free data loader for Salesforce. Leverage keyboard shortcuts for object lookups and data mapping. No security token required.
Informatica Cloud Data Loader Informatica Cloud Data Loader for Salesforce is a FREE data loading application that automates the import/export of Salesforce and Force.com data between databases and files.