Tune your guitar into Drop-D. Play the 4th, 5th, and 6th strings open,
muting the 1st-3rd strings. You can play around with a Wah, blowing
accross the strings, playing a quirky melody on the 1st string using
the open D5 as a pedal chord [one repeated as a basso continuo].
However, the trick I like the most is playing the D5 chord, letting
the amp harmonize the strings into a higher chord, and gently tapping
the whammy bar, increasing tapping strength as you go continue, until
you vibrate the open strings back into the original D5 chord. The
vibrated fade-in sounds awesome.