Every profession has its own specialized tools. For linguists (and people working in many other scientific disciplines), the main tools are the software that you use for collecting your research notes, collecting and citing references, writing papers, making presentations, etc.
Many linguists just settle for the same tools that their kids use for doing their homework — usually, not much more than Word and PowerPoint. But there are much better tools that can make your work much more efficient, and many of the best ones are free software. Follow the links below to see my personal recommendations.