1) The BB Shake
Technique: fret the string, let go of the neck and shake from the elbow, pushing up and then down on the string.
Use: wherever BB would play it that way. Most frequently a whole note with the index finger on the high E.
Satisfaction: ok in that specific context. Too fast and anxious sounding for other settings. Strong tendency to ring sharp.
2) The Knuckler
Technique: rest your knuckle on the edge of the fretboard and rotate your wrist bask and forth so the finger moves down and then up.
Use: whole notes with the index finger not on the bottom string.
Satisfaction: more likely to stay around the center of the tone. Not a bad sound. Doesn't work on the high E or with other fingers.
3) The Waggle
Technique: fret the string and move your finger down and up
Use: frequent. works with non-index fingerings, most strings. Also good for double stops.
Satisfaction: meh. inconsistent across fingers. Not always a great sound. Frequently rings too wide around the tone.
4) The Wiggle
Technique: fret the string, let go of the neck and shake from the elbow, rolling your finger forward and backward on the string.
Use: frequent. Best with ring/pinkie. Too subtle for many rock/blues settings.
Satisfaction: ok. Stays in the center of the tone. Not a bad sound. Often too subtle to bother with.