A few months ago I attended an APL-arranged afternoon where a marketing expert went through the various forms of social networking, facebook, Twitter, etc.
It was very useful because I was able to establish that Facebook and Twitter were pointless for my business but blogging was probably the way to go.
So I switched my website to a wordpress platform which has an integrated blog (dead simple, bought a theme, paid somebody to put it on the server and then just populated the site.)
I've now published about a dozen blog posts and am starting to see the results. Where we weren't even figuring for keywords like 'Landscapers Warwickshire' we're now showing 3 blog entries on the second page of Google. The same for several other keyword combinations. This is just in a few weeks and I can fairly confidently say that as I learn more, add more and tweak more this will only get better.
I know this isn't for everyone but this WILL work if you want to boost your website rankings and elevate your business profile (as well as giving a more personal view of you and how you operate.) It's powerful stuff and I'm amazed at how easy it is!