Links - Logic and First Order Logic
Oct 6 2009: added link, changed page title.
Peter Suber was a research professor at Earlham College until recently. His tutorials on logic and logical mathematics are among the most concise and accessible to be found on the web, and probably ever written.
From the preface to "Translation Tips":
In this hand-out I treat the notation of truth-functional propositional logic and first-order predicate logic as a language, and give guidance on translating from English into this foreign language.
He also has a great interest in Open Access literature.