The Book: http://c.learncodethehardway.org/book/
Here are the exercise files for the stuff I've managed to get through so far (in addition to whatever extra-credit I felt like doing):
ex1 - "Hello World"
ex3 - printf
ex4 - more printf
ex5 - printf + integers
ex6 - printf + other variable types
ex7 - math
ex8 - arrays and 'sizeof'
ex9 - strings == arrays
ex10 - loops + 2d arrays
ex11 - while
ex12 - if/else
ex13 - switch
ex14 - functions
ex15 - pointers
ex16 - structs and pointers
ex17 - Ghetto Database: file I/O, malloc and more!
ex18 - function pointers and sorting algorithms
ex19 - Text adventure game with primitive object system
ex20 - Debug macro usage