An introductory course to crypto, drawbacks of old crypto methods, (very) basic crypto analysis, designing (very) basic crypto. A must especially if Alfred Menezes is teaching.
A very good course to take to learn aspects of security. A lot of graduates have very limited knowledge of writing secure code when they go out into the industry (and even during coop).
AI! Applications of various techniques in AI to solve “real world” problems.
Advanced algorithms! A bunch of techniques in the design and analysis of algorithms. Quite a fun course.
A very good course on graph theory. Quite a bit of fun.
Course on numerical computation. Covers floating point computation, discrete Fourier transforms, interploation, splines, page rank algorithm, IVPs etc. Quite a useful course.
A good introduction to Graph Theory and a very interesting and useful course for anyone in CS or engineering etc.
A good course in critical thinking and reasoning and common fallacies.
An excellent intro PSYCH course. Useful for basic understanding of human psychology and child development etc.
Interesting course on Cognitive Processes like attention, vision, memory etc.