The MLA (Modern Language Association) style is my preferred style for writing papers - both in terms of citation and in terms of overall format. While I must confess to making small changes (based on my British English background and preference), I still adhere to most of the MLA standards when it comes to putting together research papers.
This is a guide that is useful not only for writing, but also for researching. There is a section that discusses researching both in a library and online. The guide then gives a refresher course in grammar, spelling, sentence and paragraph construction, and other elements of style that are useful in the general academic paper.
By far the most useful part of this guide is the section that shows how to reference in footnotes, endnotes, in-line/in-text citations and proper documentation of sources. While there are few elements due to new media (how does one reference a video on MPG format that doesn't actually reside on a website?) that might not be covered, this guide is fairly comprehensive when it comes to in-print, internet, and other media resources.
For undergraduate students, graduate students, academic writers and general writers, the MLA style is easy to follow, fairly intuitive in approach, and comprehensible even by those not training in such styles.