Since I couldn't find a good 4 port, I started investigating single port USB chargers. I now have a couple:
1x Genuine Apple 5W Charger
1x "High quality" ebay charger (10W - 'iPad Charger')
eBay auction: #2511277573041x Dirt Cheap hwang low charger ("10W")
eBay auction: #280919861384I am really fascinated in their compact size, and what is the absolute minimum you could get away with for a cheap, but safe, charger.
I'm tempted to tear them down myself, but I won't be able to add much value to the intellectual discussion and testing. Perhaps I should mail them to dave?
The apple one has already been torn down by others online before, so the other two might be more interesting.