Citibank was nice enough FedEx me an illustration of a misplaced modifier. The letter begins: "As a valued client, we recently mailed a letter to you regarding an incredible opportunity to receive relief on your mortgage payment through Home Affordable Refinance Program. " As far as grammar is concerned, we only need to focus on the first five words. The way the sentence is set up the first four words are a description that should be followed by what they modify, but instead, they are followed by the pronoun "we," that is the entity that makes up Citibank, which is not its own valued client.
To make the sentence work grammatically, Citibank could have opened with something like thins, "Because we value you as a client, we want to let you know about an incredible opportunity," or something along those lines.
For more on misplaced modifiers, see http://www.infoplease.com/cig/grammar-style/misplaced-modifiers-lost-found.html and my favorite grammar site, Purdue OWL,