alot of the devices i have been getting now charge from a usb port, so the kindly provide a charger wiith a usb port in one end that works oon 120v to 240v (its all switchmode stuff anywoy aand would probelly work on 60v if i tested it )
anyway the good thing is they come with a universal adaptor (so they only havve to make one power ssupply for the whole world) and they are tinny (i have one thats the size of a matchbox
combind this with a sync aand charge cable for the Z and you can charge most modern electronics
if you need to power more than one device then i recomend a very cheap hub (the cheaper the better as they dont do proper powerr managment) plug it into the charger and you have several portts capable of powering severaal devices, plus you have a hub for when you need it
if you need one then i would recomend buying somthing from hong kong on ebay as this is where i get them from (and somthing that charges off usb), i got one with my PDA from HP, one with my GPS unit, one with my bluetooth headphones and i have several others from unkown sources. if you are in auustralia and need one PM me
funny thing is that it works great if you use a Male A to Malee A cable (you need to get some adaptors from those universal usb cable kits) and plug it into one socket, then plug the Z into the host side so it controls it then plug in a USB hard drive, that waay you dont need an external power supply for the hard drive. might not work with a 3.5" drive however (they are fairly power hungry and normally need 12v as well
hope this helps
ps one last thing, try and get one that has a Amp output of 2A on the USB side, it helps if you power several devices.