Have to rep for my favorite math text that pretty much no one else has heard of: Ray Mayer's Introduction to Analysis [1]. It's rigorous, compellingly readable, and accessible to college freshmen. It was never published commercially, but decades of students where I went to school have been delighted by it, tortured by it, or both.

[1] http://people.reed.edu/~mayer/math112.html/index.html