As much of a pain in the diaper-covered area as it is, I do not travel without my laptop.  Especially when I'm travelling with my child.  Not only can it entertain him with movies and simple games, but once he and I found ourselves locked out of our destination, stuck in the middle of nowhere, at midnight, with no locally-functioning cellphone.  I was able to use the laptop to skype and get us a taxi and a hotel.

Aside from the laptop, we often have an iPod, a cellphone, a Blackberry, and a PDA loaded with eBooks (yes, I plan to ditch all but the crackberry in favor of an iPhone…and that may obviate the need for a laptop.  But we'll need to charge that too).

Despite all this interconnectivity and globalization, there is not yet a worldwide power standard, and there certainly is not a worldwide standard electrical outlet.  And even when there is, thirty years from now, the French will refuse to participate.

Thus, I found this Wired wiki article very helpful:  Stay Plugged In While Traveling.  Check it out before checking in to your hotel!