As a college student myself, I wish to study these classes when I was in my college, but they are not offered(I took most of these in Moscow instead):
- Algebraic topology.
- Real analysis (graduate level)
- Complex analysis (graduate level)
- Measure theory, geometric measure theory.
- Commutative algebra and homological algebra (at least Ext, Tor, etc)
- Riemann Surfaces
- An intro course in algebraic geometry
- Algebraic number theory.
- Classical Mathematical Physics
- Some intro course in ODE, dynamical systems (like Smale's horseshoe), and PDE.
- Combinatorical game theory.
- Elliptic curves.