In addition to understanding the languages and best practices, knowing what external tools are available is important for a developer. These are a few tools of which every web developer should be aware. They won’t all apply to every project, but they should certainly be in your arsenal.
FlashDevelop is an open-source code editor primarily designed for editing ActionScript for Flash and Adobe AIR. It provides more useful code-hinting and syntax highlighting than Adobe’s own Flash editor, including custom class code hints and automatic package includes. It can also integrate directly with Flash, allowing a Ctrl-Enter from FlashDevelop to compile and run the project in Adobe Flash, making it really easy to edit code in FlashDevelop, and do the graphical work directly in Flash. I highly recommend working on two separate monitors in this case, but it works with one as well.