Veho VCC-A008-PBP-XT Pebble Portable 5000mAH Battery: Amazon.co.uk: Electronics. Anker 5000mAh External Battery Pack and Charger for: Amazon.co.uk: Electronics. EasyAcc 5600mAh Portable Emergency external: Amazon.co.uk: Electronics. First off - I apologise if any of this is patronising; it will likely contain points which may be obvious but I feel it's right to raise them to make sure people purchase the right tool for the right job. I purchased this unit to replace a failed Anker 8000mAh unit I purchased last year. The version I'm reviewing is the 12000mAh version. I can't speak for the other capacities just yet (but I will be ordering one soon).
This unit is great, and it has come in handy all ready. Some points follow which may be good or bad for your usage. This thing has so far charged everything I've thrown at it. It charges through its Micro USB port on the side. That's if it needs recharging whilst you're away. Beware that - although it charges up over Micro USB - you can't just plug it into your laptop's USB port and fill it up. Although this might seem obvious, it's worth pointing out - you need to realise that this thing has the battery capacity of over 8 iPhone 4's.
PowerTraveller Power Gorilla Portable Power Device: Amazon.co.uk: Computers. Customer Image Gallery for New Trent iCruiser IMP1000 11000mAh External Battery Pack and Charger for iPad, iPhone 4 4G 3Gs 3G (AT&T and verizon) , iPod Touch (1G 2G 3G 4G), HTC Android EVO, Blackberry, Kindle DX, Samsung Galaxy S, Droid, Nintendo, Sony PS.