We live in an age of wonderful expansion in the availability of archival and early imprint materials relating to Mormon Studies. Google Books is a well known example. The Church of Jesus Christ of Latter-day Saints published thousands of images from its various collections in a DVD library called Selected Collections (2002). Additionally, the Church is adding to its extensive online collections at archive.org. You can find help here at history.lds.org.
I want to focus a bit on the Selected Collections library, since it contains a large panorama of materials, from the Manuscript History of the Church and the Joseph Smith Collection, to the letterpress books of Brigham Young and the papers of George A. Smith, long time Church Historian. The General Church Minutes series is especially interesting and valuable. Originally available only on DVD for a substantial price (more than a grand) you can now access it online[as noted in the comments, you’ll need a BYU Net ID to get past the blockade here] at the BYU Mormon Studies archive.
For anyone exploring Mormon Studies with a need for fundamental archival research, this is a great place to begin. You will be missing the context of many of these documents, so buyer beware. The collection does have a few limitations, but this is not a review of this excellent resource. I simply recommend that you take the plunge and read! The Journal History Index is a fun read for geeks. Just sayin’. Enjoy.