Cyclopaedia.org, a very thorough compendium. Includes links to the University of Wisconsin Digital Collections complete digitization of the 1728 edition and notes on navigating within that site.

Wikipedia entry on the Cyclopaedia.

Britannica Online entry, which points out the relation to Brockhaus.

Ephraim Chambers:
Obligatory biographical Wikipedia entry (Lists several good references.)

Articles:
Yeo, Richard R. 1948- "A Solution to the Multitude of Books: Ephraim Chambers's Cyclopaedia (1728) as "the Best Book in the Universe " Journal of the History of Ideas - Volume 64, Number 1, January 2003, pp. 61-7. abstract here.

---. Ephraim Chambers's Cyclopaedia (1728) and the tradition of commonplaces. Journal of the History of Ideas. Jan96, Vol. 57 Issue 1, p157.

Only semi-related, but don’t want to lose it:
Dacome, Lucia "Noting the Mind: Commonplace Books and the Pursuit of the Self in Eighteenth-Century Britain." Journal of the History of Ideas - Volume 65, Number 4, October 2004, pp. 603-625.