Excellent resource, especially for students who have to use multiple citation styles. In-depth look at Chicago, MLA, and APA, as well as lesser known styles, like AAA, AMA, and those for math and science. It does not make any mention of Blue Book style, which is a tad unfortunate, but most people using that style will probably already have the Blue Book manual.
For Chicago style, it provides an example of a first note, short note, and bibliographic entry, which is incredibly helpful. MLA and APA, as well as Chicago, cover standard resources, as well as more obscure ones, like sheet music, blog entries, and advertisements. Multiple examples of one type of citation are given as well, making it easy to see what you can leave out, or how to format a citation if certain information doesn't exist.
Highly recommended, especially if you use a lot of odd and obscure types of sources like I do.