This is old news, but I think still worthy of a post, as many folks aren't familiar with Google's AdWords Preview tool.
This little app allows you to see your PPC ads displayed as others see them.
For example, you can check that your ads are or are not serving correctly in different geographies (without having to hop a plane overseas ).
Also, you can avoid the filtering that often occurs of your ads served into your office IP. Google stops serving certain ads to certain IPs if those IPs have unusual click patterns, either too low or too high. Which is exactly what often happens to your ads at your offices -- many people search on terms that bring up your ads but few of your own folks ever click on your ads.