There are many companies on the web that do PR, many of which are SEO companies. Some do their own in-house thing; others outsource, but still charge you royally. A simple search for SEO PR or PR service turns up a good list of companies. Those companies that don't do SEO are usually well aware of it and have incorporated SEO techniques into their craft. You can also try SEO companies, but watch out for outsourcing, which many companies do.
Try getting an exclusively PR service company that is familiar with SEO and understands link value, instead of leaving the task to an SEO company.
Creating PR Stunts
Public relations stunts create a lot of publicity and links, but may backfire, depending on how you approach them. The goal of a stunt is get a lot of attention and links. To create a stunt you can trash someone, claim to make a mega invention, start controversy, talk about subjects no one wants to talk about and all other sorts of goofy stuff. The risk of this strategy is that a negative image associated with the stunt may stick with the brand and in fact destroy it.
A good example of a "PR stunt" was Aaron Wall's lawsuit with Traffic Power. Though completely accidental, it created a lot of controversy, and as a result his name was mentioned in the Wall Street Journal, NY Times and throughout the blogosphere. It was a blessing in disguise, and it helped Aaron get his business off the ground.
Partner up with a Brand
Brands like Google, Apple and Nike have immense brand value. If you partner up with them or someone equivalent, their brand power will be partially passed on. Though it's not much in the way of PR exposure, it's a good trust builder.
Bloggers Speak of Public Relations When the Speak of Linkbait
The most well known PR trick pulled by SEOs is the link bait article through social media like Digg, Sphinn and others. It has maintained the basics of traditional PR, where to get the needed exposure you must first provide the turf, but social media crowds replaced the journalists. The essence stayed intact - good turf means good exposure.
Both forms of PR, the traditional and social media, require connections to promote the story (less with social media), but both serve the same purpose - links and brand awareness.
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