Tate Hanson, of ClearNet Security, produced an excellent web application called nmapTweaker that helps perfect nmap syntax.
From the article:
We’re playing w/RoR and building a few web apps. I wrote a quick and easy one that helps you build a command line for nmap, nothing particularly special.
I did add some extra content: tuning tips, examples, and a time estimator. Basically you can use it to build a command line, then copy and paste it to wherever you want to run it.
It does not do syntax checking for nmap options which require input yet (e.g. targets, output file name, etc.), but the app does do some error checking for conflicting options.
It’s a little rough, but hey, it might save you a few minutes of time if you’re not an nmap option sage.
Good work Tate.