just a quick sampling of some stuff I did in my CS major:
* wrote a Pascal compiler from scratch
* implemented a variation of FAT32 in the linux kernel
* implemented a simple pipelined MIPS arch in vhdl
* benchmarked different versions of a parallel algorithm on a HPC cluster to see how it scaled on core count
* implemented lots of data structures in c++
some of that stuff applies directly to the work I do now. I landed a good c++ gig straight out of college, and I really appreciate all the tough c++ projects we had to do in school. amusingly the Pascal compiler also turned out to be relevant, as I now help maintain a compiler for a proprietary dialect of Pascal at work. the cpu arch, HPC, and linux stuff isn't directly applicable to my work, but the linux project was a good exposure to working in a large codebase.
not everything in a CS major is going to be directly applicable to your career, but a good program will give you strong foundations for any specialty you branch into later.