Air adapters
Would pay a visit to ebay, got my very nice targus one for under £20, around £80 in the shops. The Powertips are specific for each laptop, but these can be had from targus free, just give them a call and tell what laptop you have.
The newer ones do cigar lighter 12V power for the car, the aircraft seat adapter and mains voltage, so you only need to take one. My targus one charges the mobile phone, laptop, ipod etc etc. Well worth the money.
high-flyer