Classical Logic - http://plato.stanford.edu/entries/logic-classical/ Introduction to classical logic, including completeness and Löwenheim-Skolem theorems; by Stewart Shapiro.
Mathematical Logic and Foundations - http://www.math.niu.edu/~rusin/known-math/index/03-XX.html From The Mathematical Atlas, a resource of mathematics maintained by David Rusin. Extensive resources related to logic and set theory.
Computability Logic Homepage - http://www.cis.upenn.edu/~giorgi/cl.html Main online source on computability logic - a recently emerged formal theory of computational tasks and resources. Maintained by G.Japaridze.
Mind Versus Goedel by Damjan Bojadziev - http://nl.ijs.si/~damjan/g-m-c.html Compares the mind to advanced computers and artificial intelligence, as Goedel would possibly view them.