Portable power strips are very useful espeically during travel. Good, useful portable power strips have multiple outlets, and multiple USB power ports as well. They are also light and compact enough to be fit into your travel bag. Some of the good models can fit in even the big AC adapters.
Keep in mind that a power strip shoul never be substituted for surge protectors, as they can provide only a modium of surge protection. At least make sure your strip comes with as high 'joule rating' as possible. Check details and look for 'joule rating.'
The best portable power strip with USB: Accell Home or Away Power Station (three AC outlets, two USB power ports, compact size)
The second best portable power strip with USB: CyberPower CSP300WU
The best portable power strip for traveling abroad: PowerCube ReWirable USB + Plug (four international plugs, 100V to 250V rating)