This page lists software that I think is worthwhile using or, at least, trying.

Statistics
• IBM SPSS
• R
• Statistical packages on Wikipedia

Visualization
• MS Excel
• Google Fusion Tables
• Impure
• Tableau
• Gephi

Text Manipulation
• MS Word
• Notepad++
• Google Refine
• Textstat

Network Analysis
• Pajek
• Gephi
• UCInet
• List of SNA software on Wikipedia