Windows: "Everything" (that's the name). A lightweight, fast and advanced (if you want it) file search engine.
Linux: Most tools of course, as they are made with the Unix philosophy, but these days I'm most surprised by print drivers for Linux. Where in Windows the printer is always magically offline or slow, from Linux I can print and scan very reliably.
Vim is also worth learning, it makes editing much more... relaxed I guess. No longer have to move your mouse to the arrow keys or even the mouse/touchpad to scroll or select. It also helps that it exists on nearly every Unix system you'll ever connect to.
And finally I recently discovered LaTeX, which could be described as markdown on steroids. A little more difficult to get into, but it's easy to create professional documents and have a plain text source (which works nicely with git and other unix tools). If you have trouble getting started in LaTeX, ask me (comment here or see my profile), I also didn't know how to get started for a while.
Edit: Another Windows tool is Notepad++. I have not seen the likes in Linux when it comes to robustness. It has all the basics you need for handling any sort of file that involves manual editing, binary or plain text. If there is no binary editor available for your file of choice, or if you just want to have a quick peak, Notepad++ will do just fine. Beware of really huge files, although I have seen it handle some big things on low RAM machines too.
Linux: Most tools of course, as they are made with the Unix philosophy, but these days I'm most surprised by print drivers for Linux. Where in Windows the printer is always magically offline or slow, from Linux I can print and scan very reliably.
Vim is also worth learning, it makes editing much more... relaxed I guess. No longer have to move your mouse to the arrow keys or even the mouse/touchpad to scroll or select. It also helps that it exists on nearly every Unix system you'll ever connect to.
And finally I recently discovered LaTeX, which could be described as markdown on steroids. A little more difficult to get into, but it's easy to create professional documents and have a plain text source (which works nicely with git and other unix tools). If you have trouble getting started in LaTeX, ask me (comment here or see my profile), I also didn't know how to get started for a while.
Edit: Another Windows tool is Notepad++. I have not seen the likes in Linux when it comes to robustness. It has all the basics you need for handling any sort of file that involves manual editing, binary or plain text. If there is no binary editor available for your file of choice, or if you just want to have a quick peak, Notepad++ will do just fine. Beware of really huge files, although I have seen it handle some big things on low RAM machines too.