Harmonics!

I'm writing a trio for violin, horn in F, and bass clarinet. I'm already using touch-four harmonics in the violin part, but I want to know other harmonics as well. So, what are your favorite harmonics/multiphonics for these three instruments, and how does one write/play them?

The two E harmonics are great: barely touching in first position the A on the E string sounds the E two octaves higher and the natural E harmonic an octave higher. Of course these work with the other strings though the 'first position' harmonic gets a bit crappy when heading towards the lower strings such as D or G. You can only play this harmonic if you bow it really quickly so don't use it as long passages - use the one up at the end of the fingerboard for that.

The touch-four harmonics - I guess you mean artifical, i.e. playing a note and then barely touching the note a fourth higher to create the harmonic?

That's all I can think of as regards the violin harmonics. The cello's harmonics are much more varied.