The Alien Bees Vagabond Mini is a lithium battery pack which gives USB and AC power, and includes battery, inverter, and charger. I originally bought it to run photo flashes (which it does quite nicely), but I also use it to run my laptop, and it will also run any AC device less than 300 watts.
After seeing the low quality available for other lead acid battery packs, I decided to build my own. Then this came out. The whole package is about $40 more than the price of an equivalent battery pack, and it is a complete package. Other people have verified that it has a “PureSine” inverter.
There are some reports of them not working in 120 degree ambient temperatures of the desert outside of Dubai. They can also apparently be burnt if you run them at 500 watts, and keep pulsing them at 2kw for several hours. I suspect that it is the continuous load and high temperatures internally when pulses are demanded which causes the failures.
Take a look, it really is a cool tool for portable power, and for powering strobes.
[Photo guru Rob Galbraith has a very thorough review of the Vagabond Mini for those interested in specifics.--OH ]