I wish I could upvote twice.
Lamport's writing is _very_ accessible ( at least to this college dropout ) and I really enjoyed reading Time, Clocks and the Ordering of Events. Paxos Made Simple is another favorite: http://research.microsoft.com/en-us/um/people/lamport/pubs/p....
Time, Clocks and the Ordering of Events in a Distributed System (seminal paper which won various awards): http://research.microsoft.com/en-us/um/people/lamport/pubs/p...
That link actually takes you to a complete list of Lamport's works.