Vocal Special FX

I try not to get to heavy-handed with FX on a lead, especially if good and exposed. However, using harmonies/background vocals can fall into the "fair game" category for playing around.
 
A useful Melodyne tutorial is their "Reverb shimmer" one, which touches on some nice techniques. If you knock the consonants off words, it opens up a lot of possibilities on what can be done with the rest. There is a lot more leeway for adjustment when only the vowels/formants are in play. That example is fairly "extreme," but the same idea applies.
 
Barring FX to the entire vocal, I find adjustments simpler if moving the lead material to a second track that will be modified. In my experience, accentuating material is more effective than modifying an entire track (especially a lead).

Hey mettelus,
 That reverb shimmer trick looks interesting. I'm thinking about trying it out soon. It looks like you can get some pretty interesting colors using that trick in conjunction with choruses, phasors, flangers, harmonizers, stereo-widening etc... especially when you start mixing and panning those sounds to taste. You definitely don't have to be heavy-handed with a technique like that to get a unique sound. I'm sure playing with the formant properties in Melodyne can broaden the palette substantially.
 
The technique mentioned in this video is something that enriches the vocal as well:
http://therecordingrevolution.com/2015/07/09/the-vocal-air-trick-in-mixing/
 
I use it quite a bit. It gives the vocal a hi-fi sound.

If I'm truly after "unique", by definition that means eschewing the normal "go-to" techniques and thinking outside the box. However, "unique" is rarely the goal. A better adjective might be "characterful", IOW not strictly unique but also not humdrum.
 
There is no effect that's off-limits. That includes effects normally associated with guitars and synthesizers, such as a Leslie emulator or a fuzzbox. Experimentation is encouraged.
 
But you asked for a specific technique, so OK, here's one: parallel distortion. Run the vocal through a distortion plugin, preferably one with a wet/dry mix control. A useful one that's also free is Boogex from Voxengo. If you don't have a distortion plugin with a wet/dry knob, insert a send and place the effects on a bus. This has the added advantage of being able to effect the distortion component further, such as placing a chorus plugin after it.

i think the most unique vocal sound you can get,
is the most dry, hot, in your face unaffected pure vocal you can capture.
 
it's your voice, in all of it's UNIQUENESS (and for better, or worse)