Just came across this free plugin for your wordpress website, that can help you increase your blog exposure and build loyal readership. Also has the ability to detect the visitor’s search keywords from major search engines and automatically display related posts under or above the greeting message.
WP Greet Box –
This plugin will greet your web visitors with a welcome message
that is tailored to how they visited your site. If they got there via Digg, it will
prompt them to Digg your post. If they found it through a Twitter link they will
be prompted to retweet and follow you on Twitter. This is a great way to get
people to interact with your blog.
To install just go to Plugins in your dashboard and click on add new 
Next type in name of plugin WP Greet Box WordPress Plugin and click on search plugins
You will see a plugins page click on install now
next you will be shown the plugin page,scroll down until you find the WP Greet Box plugin and click on activate. And that is it. Done.
this is a screenshot showing a different greeting message to your visitor depending on which site they are coming from.
If you don’t have the time to install this plugin yourself, I can do it for you.