The object of this exercise is to provide contact information, not to do background searches. There are plenty of fee-based services around if that is what you are into. Given the increasing concern for privacy, much personal information has been removed from the Internet in the past 3 years-most notably social security numbers, medical information, and the like. Most general information is compiled from online directories and from regional Bell telephone books.
Some services go beyond that.
There is also a set of links for searching heirs and beneficiaries as well as an option to place a message on their message board so others can find you. Be careful about leaving information on sites such as this, or you may get what you don't necessarily wish for. I usually test services such as this by opening a free e-mail account and then seeing what pops up in the weeks to come. Use it to link to yellow and while pages, public records, and government resources. The government links are especially good.