Custom Content by Country is without question, probably one of the most useful plugins I've found for my website.
It displays different content to visitors depending on where they are visiting from. I use it to tailor my adverts to my visitors, especially useful for Amazon Associates where referral earnings and tracking cookies do not pass between the different Amazon stores.
I had a problem trying to get the script to work outside of WordPress and upon submitting a request to the support it was answered within a day and resolved within a few messages.
The support really go outside of their way to help you personally.
A free plugin, but the value that it has bought to my site I will most likely by the team a few beers to say thanks. I urge others to do the same!
One very happy 'customer'