Sending out press releases is a great way to get some free business promotion. The only requirement is that your press release has to actually contain information that is newsworthy, and be engaging enough to get people's interest.
Has your business recently expanded? Do you have a new product? Have you been involved in some promotional activity such as sponsoring a charity event? Have you or your company recently won an award?
Don't keep it to yourself - shout it out to the world, via a press release!