I use three applications that make my life a breeze while editing missions. Thought it would be a good idea to let others know.

TreeComp

TreeComp (http://www.xs4all.nl/~lploeger/TreeComp3.htm) has to be the most useful utility I use. In conjunction with WinDiff (see below), this utility is used to compare mission directories against, other mission directories, FTP sites and ZIP files. It showing the differences between two sources graphically, and is perfect for working out what has changed between script versions and what differences there are between your scripts.

A quick note is that in v3.x, make sure you turn off Monitoring Thread option, as it used to crash the application frequently. Other than that, I use Size and Content options when comparing scripts, to ensure I'm seeing all the changes.

WinDiff

Used in conjunction with TreeComp, I usually download (http://www.grigsoft.com/windiff.zip) and save WinDiff.exe in my C:\Windows directory. This allows TreeComp to run it, when you double-click on a changed file, to show you graphically what has changed between your files.

Squint

For me, this was the best find ever (http://www.armaholic.com/page.php?id=11818). The amount of syntax and coding errors it has informed me about before I ran the mission are innumerable. The interface is a little clunky, but the extra features are fantastic.

ArmaEdit (I use Squint these days)

I'm told there is a better editor than this one, but I'm still using it. ArmaEdit (http://www.armaholic.com/page.php?id=1455) will highlight your scripting code coloring keywords, comments and strings, etc. Makes editing easier and will prevent silly mistakes like forgotten comment markers.

There is an ARMA2 keyword update (http://www.armaholic.com/page.php?id=8354), which updates the keyword list for ARMA2.