Your site visitors care about one thing - how you can help them get what they want.  They don't want to read all kinds of long, boring prose about how great your company is or it's history, nor do they want to have to give you their name and email just to be able to view more information about your products or services.  Your visitors want a solution to their problem - whether they're looking to buy a product online, or whether they just want a good laugh from your joke of the day.  Don't scare them away by demanding information from them before they're ready to provide it to help themselves.

I thought the following pretty much went the way of the 90's, but recently I was researching a product and ending up on a major company's website, only to find that I couldn't even reach the product information page without encountering "let us know who your are!"  Well....NO!  I immediately left the site and returned to Google, and the company lost a sale to another site.  There are too many competitors out there for you to alienate potential customers by demanding information from them before you've earned it.