I own a small book on Lattice theory published by Dover. Unfortunately, since I bought it almost a year ago, I have gotten nowhere in its study.
What I am asking for are freely available papers that use lattice theory in a substantial way to prove theorems about mathematical objects I am already familiar with and interested in: groups, rings, modules, topological vector spaces, logic, $\dots$ to help me get excited about lattices, and potentially give me a reason to study them for their own sake. Short articles ($\sim10$ pages) are especially appreciated (but not necessary), as are those articles that helped you become interested in lattice theory and convinced you of their utility.
I know this is potentially difficult, as I imagine most 'interesting' applications of lattice theory require advanced material on lattices, but I am willing to take certain theorems on faith, and have several lecture notes on lattice theory saved on my hard drive for reference.
If combinatorics counts as an application for you, you can take a look at Chapter 3 of Stanley's Enumerative Combinatorics. http://www-math.mit.edu/~rstan/ec/ec1/
Formal concept analysis is another example: http://en.wikipedia.org/wiki/Formal_concept_analysis .