Just got word of a new freeware program from X-BIOS and it's called NullSoft instalation script editor version 1.0 alpha!

This editor for all users, who use NullSoft NSIS installation system.

IDE features:

Powerful text editor
Syntax highlight
Completion proposal
Compiling from IDE
Error detecting
Wizard for fast creating script

Download NullSoft instalation script editor v1.0 alpha