I don't know if I have an answer for you, but I'll let you know the results of an experiment I just started doing: 100 pushups a day.I never saw any results from tricep extensions in the past, so this is my last ditch effort to tone my arms!
I can't do the pushups all at once of course, usually 20 at a time throughout the day. They really work everything in the upper body, even your stomach and back, which is an added bonus because I HATE crunches. But I do feel it in my triceps, so I am trying to do the same thing as you...get rid of that jiggle! It's only been a little over a week....I'm hoping to see some improvement in 2 months. I'll post the results when I'm done, one way or the other!