The Harvard Law Review has launched an online version of The Bluebook:  A Uniform System of Citation.  From the press release:

The standard citation guide for American legal writing, The Bluebook is widely used throughout legal practice, by paralegals, attorneys, professors, and students. …

The new online format responds to longstanding requests for a fully-featured electronic edition of The Bluebook that is easier to search, use, and teach. It allows practitioners and students with jurisdiction-specific or publication-specific citation rules to combine them with the general rules of The Bluebook, and it makes an essential tool of legal writing fully accessible to the visually impaired. The online version is also designed to allow future editions to address a wide array of foreign, international, and administrative material much more fully than is possible in the confines of a small printed handbook.

The cost is $25 for a 1-year subscription ($40 for two years and $55 for three years).