1) Interest in non-mainstream programming languages: 95% of developers program in either some flavor of .NET, Java, or C++. How many people program in Groovy, Prolog, Lua, Forth, D, OCaml, Erlang, Haskell, or Lisp?
In my experience, mastering the idioms of a these oddball languages lets you approach problems in mainstream languages from a novel angle. And if for nothing else, someone who learn an oddball language for fun shows a real passion for programming.
2) Algorithms and data structures: most CRUD and line-of-business development isn't algorithmically intensive, but there's going to be a time when you encounter a problem which can't be solved using your language's built-in linked-list, array, or hashtable data structures.
Just to name a few examples I've seen in the real world:
- I worked on a project which contained a requirement to flag images of insurance forms tilted beyond a threshold angle.
- On another project, I worked on a project which required writing a simple decision engine: scanned items are assigned one of a dozen or so statuses (new, activated, pending, voided, cancelled, etc), and there is some non-trivial business rules which need to be evaluated to determine state transitions. The problem at hand can be modeled is modeled very easily and naturally using finite state machine.
- Recently, my project's requirements demanded the need for a thread-safe priority queue.
There are simple and efficient ways to solve the problems above, but in each case the original developer implementing the functionality had no experience with algorithms and data structures. The resulting code was a disaster.
Hiring managers often don't understand what it takes to write software, they accept that everything is "magic".
3) Elegant code: You'd think the fact that maintenance accounts for 80% of the cost of software development would make companies emphasize a high quality of code, but companies just don't care.
Your code is invisible to the end user -- as long as the product sells, your company doesn't care whether its a masterpiece of algorithmic elegance or pieced together with messy hacks. "Does it work? Sort of, you say? Good enough, package and ship!" (sighs)