Classical Logic: Introduction to classical logic, including completeness and Löwenheim-Skolem theorems; by Stewart Shapiro.
Computability Logic Homepage: Main online source on computability logic - a recently emerged formal theory of computational tasks and resources. Maintained by G.Japaridze.
Introduction to Mathematical Logic: Hyper-textbook for students by V. Detlovs and K. Podnieks.
Logic: Wikipedia article.
Logic: Open Encyclopedia entry. Hierarchically organized by subareas.
Math Front: LO Logic: Front end for the logic section of the mathematics e-print arXiv.
Mathematical Logic and Foundations: From The Mathematical Atlas, a resource of mathematics maintained by David Rusin. Extensive resources related to logic and set theory.
Mathematical Logic around the World: A rich collection of links to logic-related websites.
Mind Versus Goedel by Damjan Bojadziev: Compares the mind to advanced computers and artificial intelligence, as Goedel would possibly view them.
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