I haven't done one of these in a while.
Some whales are far more vocal than others. The toothed whales, such as orcas, dolphins, and belugas are really quite vocal, including using echolocation to locate their prey. Baleen whales do not echolocate, but are still very capable of producing sounds, however they vocalize purely as a form of communication. Their calls are also very high frequency and will only travel rather short distances in the water. Baleen whale song, such as humpback or blue whales, is commonly sold in the form of CDs that are meant to be relaxing. These songs are love songs and are incredible low in frequency, carrying for hundreds of miles. In fact, the frequency is so low that many of the recordings have to be altered so that we can even hear them! Whale song usually changes from year to year, depending on what is "trendy."
There is a fairly famous whale of an unknown species that was first identified by the US Navy due to its unusual song frequency of 52 Hz. Not only does its song match no other whale, but its migration patterns are also strange. NOAA has a page that seems to suggest that the whale may be an unusual blue whale. It's also thought by some that the lonely whale may be a hybrid of some sort, or be the last remaining member of an otherwise extinct species.