Often, I have found a need to draw something to explain what I have in my mind as a high level design for a particular software. I don't really mean in the UML diagram kind of sense, but just boxes, connections between them etc..., some simple ones but at the same time crisp and clean looking ones, which I can present either as images or in slides.
The best thing so far for me has been drawing something on a paper and then taking a picture of it and sharing. It has worked most of the times, but at times trying to put together something that fits within a paper's size and then making any notes in there clearly visible in the image has been difficult.
I have tried a few online tools too. Tools that require you to create the diagram online or tools that require you to have a specific browser plugin for them to work.
Does anyone here use any offline tool which is just a native application and is easy to use for such free from diagrams? I'm on Linux and have tried gimp but I haven't felt productive with it for such uses.
DOT could be used with more annotations than I use, getting the base diagram and then annotating it "by hand" seems fastest.