Thank you all for your replays.
I'm planning to build 8-sockets power strip, AC 220V. Two of them should be capable of 10A, the rest can be 5A.
My plan is to run i2c over regular usb wire. This way I will have an option to add the second power strip to USB hub.
I'm planning to use the following relay (or similar)
http://www.ebay.com/itm/5p-JQC-3F-T73-DC-12V-5PIN-125-250VAC-28VDC-Power-Relay-NEW-PB1-/170713872646?pt=LH_DefaultDomain_0&hash=item27bf56f906
with coil power 0.36W (http://www.langir.com/htm/pcb-relay.htm)
TPIC6B595 looks very interesting. Pros: no need in port expander and lower voltage drop than with ULN. Cons: slower, but not sure how slow compared to relay's response time. Anything else?
Do I understand correctly that instead of using hub for connecting the second strip I will need to have a cascading port on the first one?