Chris describes in detail some serious mistakes you can make when choosing persona names, or other artificial names on prototypes, and how to avoid them.
What’s best: he points out a Random name generator that lets you generate any number of realistic English names for prototypes and testing scenarios that are neither funny names (“Ken Hartley Reed”) nor celebrities you didn’t know because you’re not living in the US. Names from the US census are randomly recombined and automatically googled for uniqueness.
Also, the Name Voyager let’s you find whether the name you’re considering fits the age range of your persona.
Update: people are not the only data you’ll need – thanks James for reminding me!
Dotomator (http://www.dotomator.com/) generates wonderful company name lists from component lists you can select from several categories. They even look up whether the domain is still available. My favorite is the tech/hardware combination with such wonderful results as Venturesink.com. But nooo, no funny names in companies either! Well, anyway, with this tool you’ll get a reasonable-looking suppliers list in no time!