www.criticalthinking.org.uk (an excellent guide to the AS Level papers and some really useful case studies)
Multimedia Course from Roy van den Brink-Budgen (free sample available on his website)
Cambridge Assessment Seminar on the role, value and impact of Critical Thinking
OCR A Level in Critical Thinking (legacy)
OCR A Level in Critical Thinking (current)
OCR Thinking and Reasoning Skills (Level 2)
AQA A Level in Critical Thinking
Battleground God - a test of logical consistency
Tim van Gelder's Critical Thinking on the Web
Constructing a Logical Argument
Are You a Moral Relativist? Quiz
A List of Fallacious Arguments
Rationale - Argument Mapping Software