A technique i saw a great guitarist use was what has since been described to me as 'artificial harmonics'. It's where you place your fretting hand down on the string like if you where just playing a normal note, but with your plucking hand you tap (not like with finger tapping, but more like a gentle flick) the string and octave above where you fretted it...
I hope this is making sense...
Another way to describe it is that you are using your fretting hand as a new nut for that string/strings, and therefore tapping the 5th fret (from your finger), 7th, 12th, 3, 3 2/3, 4, ext, will all produce harmonic tones...
The downside is it can have a hard sound, but you can change that when you learn to flick gently
kepp rockin' it up high

(even if it's only to get back at that overly loud guitarist)