Sometimes I want a quick harmony or several voices of harmony.  Nectar works well for that, but up until now I have copied the vocal clips I wanted to harmonize and pasted them in another track with Nectar loaded in the FX Bin.  In Nectar, I Solo Voices.  The result is the Lead Vocal on Track A and the Harmony Vocals on Track B.  But, the cutting and pasting is kind of a hassle.  Recently I read some posts here and elsewhere about automating plugins and tried this instead.
 
Insert a Bus and load Nectar.
Set the Harmony Module to Solo Voices.
Insert a Send on the Lead Vocal Track.
Automate the Lead Vocal Send (on/off) so that Nectar is triggered as desired.
 
(One thing I'm not sure of is how the other modules in Nectar are triggered by the Lead Vocal Send.  I leave them Bypassed.)

Great tip!!!

I have automated some plugs & synths in the past using a midi envelope to control certain parameters and functions as well..... it's another way of doing it.  

Hey, Herb:)

That's an interesting idea.

How about sending the lead vocal to a harmony track instead of a bus? Then maybe you could mix overall more conveniently or send the two tracks and other vocal tracks to a common vocal bus etc.

This recent free tool might fit in to your idea:

http://forum.cakewalk.com...nyone-m3158831-p2.aspx