The simplest way to find someone is to use an Internet search engine like Google. Most people have some information on the Internet. Do not simply search for their name, especially if it is common. Search for their name in conjunction with one or two other pieces of particularizing information. This would be things like address, zip code or job title.

Particular Search Engines:

There are search engines particularly created for finding people. Most sites you can search by name, phone number, or address. Thus, you can specify the state or, in some places, the country.

YouTube:

You can set up a YouTube account and upload a video with a message that you are trying to locate "x" person. You should tag both their name and your name so that when people search YouTube your video will appear. You may also want to add other content to your YouTube channel given that the more people view and subscribe to your channel the higher the probability that the person you are trying to find will see it.

Website/Blog:

You can set up a website or blog that is dedicated to finding this person. There are many free websites that have free hosting such asblogger.com and blogspot.com.

Facebook/MySpace/Twitter/LinkedIn:

These common social networks are great places to find people. They are all free and you can both set up an account and search existing accounts for lost persons.

Private Investigator:

Depending on your urgency for finding the person and your financial means, you can hire a private investigator. Prices will vary significantly. None, however, will be cheap. The National Association of Legal Investigators has compiled a list of investigators that you can search by state or zip code.