For years I have looked for a "minimalist" portable and universal charger and cable system to support our phones, cameras, GPS units and other electronic devices while traveling.
Tired of hauling around a bag of chargers and different cables to match the varying connection ports on each device, I finally initiated an exhaustive Internet search accompanied by lots of contact emails to clarify specs, etc.
All of this effort has paid off, however, in the form of a single charger that works in vehicle 12V sockets as well as international power mains (with appropriate adapter plugs) from 90-240 VAC, AND a single cable with interchangable Tips at the device end.
This has to be one of the most useful combos I have ever run across. Surprisingly, I have found no single vendor that carries as clean of a solution as this one. But by purchasing from two sources, you can have the best-of-breed solution possible, as far as I am concerned.
The portable Charger is made by Naztech and sold by a number of outlets. IT IS THE ONLY 3-IN-1 CHARGER I HAVE FOUND THAT WORKS WITH ALL OF THE iPHONE MODELS, INCLUDING THE 3GS.
Note that the 3GS design incorporates a different charging circuit than all prior iPhones. It is desinged to ONLY use the USB bus pin on its input connector for charging purposes. Previous iPhones supported charging from two different pins; the USB bus pin (limited to 5 volts) and the Firewire pin, which can carry up to 18 volts.
Most 3-in-1 chargers drive the USB pin when plugging into a 12 volt vehicle socket and the Firewire pin when the charger is plugged into household power (110/220 VAC). These chargers (which is most of them) will not work with the 3GS iPhone, but the NazTech n300 will!!!
The n300 3-in-1 charger is not much bigger than half a candy bar. Since it is a bit larger at one end, it so reminds me of a penguin that is why I call mine. . . the "Penguin Charger"
It has a 12VDC connector at one end and foldable power mains prongs at the other end, along with a standard USB connector.
The power plug blades fold back into the body to yield a slim, smooth package.
More info from the manufacturer here >> http://naztech.com/products.php?id_prod=46
The price for the Penguin can be as high as $50, but I bought mine at http://www.cellularaccessory.com/n300-9758.html for a 75% lower price!!!! I initially ordered two and was so happy with them that I ordered 6 more.
Rounding out my travel kit is a GeMadic retractable USB cable with interchangeable tips. You only then need a collection of tips to charge/connect with virtually any device you might have.
Then, at the GoMadic TipExchange, you can buy extra (a iPhone tip comes with the above cable assembly) end tips to fit with any device >> http://www.gomadic.com/cabletip.html
To easily carry these items I purchased a small 3" x 4.5" leather three compartment zip bag at a leather shop. This gives me a compartment for the Penguin, one for the cable, and a third for the various Tips we carry. This gives us complete travel charging and synchronization for ALL of our devices.
NOTE: For maximum flexibility, when you buy the GoMadic cable order the USB and NOT the Charger option. Since the Naztexh n300 charges over only the USB bus (rather than also Firewire) it works with standard USB Sync cables, thus eliminating yet another Tip (one for charge and one for sync).
Hopefully you will find this as useful a charge/sync system as I have.