Have you already considered the whole "picture your audience naked wearing only black socks" thing?
- Use profanity sparingly... when you really want to emphasise a point... if you use it thru out, it de-sensitizes yer audience... coincide yer swearin with the appropriate increase in decibels...
- be animated... drive yer yer middle and index fingers thru a persons sternum/solar plexis to let them know yer serious...
- if someone ain't payin' attention, feel free to flip their seat over (with them in it) to let everyone know you appreciate their attention...
- feel free to berate yer audience if they don't get/agree with what yer sayin... references to mothers, sexual practices are most effective here...
These have proven effective fer me... heck... I've never been asked to speak to the same crowd twice... I guess I made my point the first time...