Software

Corpus creation

• BootCaT — build corpora using the web (free)
• KWiCFinder — Key Word in Context Concordances directly from the Web (registration is required but the program is completely free)

Text editors

• Notepad++ — a powerful text editor (free)
• SciTE — another fine text editor (free)

Concordances, collocations & corpus analysis

• AntConc — concordance program for Windows, Macintosh OS X and Linux (free)
• TextSTAT — a simple tool for the analysis of texts (free)
• ParaConc — bilingual or multilingual concordancer (non-free, demo version available)
• Wordsmith Tools — lexical analysis software (non-free)

PDF conversion

• A-PDF Text Extractor — offline batch PDF->Text conversion (free)
• PDF2text — online PDF->Text conversion (free)
• PDF Creator — create PDF files from any application (free)
• OpenOffice — office productivity suite (i.e. alternative to Microsoft Office) capable of producing PDF (free)

HTML conversion

• HTMLAsText — offline batch HTML conversion (free)

Character Encoding Tools

• Character Encoding Converter 1.1 (free)
• iconv — nice little command-line tool that converts between many encodings