The Logic Machine: This website "provides a vareity of exercises, from questions about basic concepts such as validity, to wff constrtuction and translation, to proofs, truth tables, and countermodels."
The Power of Logic: This website is intended to be used with the 4th edition of the text of the same name, but may be of interest to anyone studying logic. You'll find many logic exercises and resources for creating your own truth tables, proofs, and Venn diagrams.
The Fallacy Files: This website includes useful discussion and examples of logical fallacies. It should be noted that logicians sometimes use different names to identify the same fallacy.
