How is this the top post in HN right now?
If I post about Tom Moore's fantastic "Six Ideas that Shaped Physics" textbook series (http://www.physics.pomona.edu/sixideas/), which is based on a career's worth of experience and many of the best ideas from the active field of Physics Education Research, is that also a front page link? (I'm teaching my Modern Physics course out of two of those volumes this semester, and the students seem to really like it.)
"Six no bullshit ideas that shaped physics" Boom! front page.
It's a math textbook. There are thousands of them. What makes this one so special? The fact that it says, "No B.S."? It has a fancy webpage?
It looks pretty standard, and isn't even very cheap.
It fits in you (man) purse, yet covers the equivalent of 2000+ pages in mainstream textbooks. Also, it covers both calculus and mechanics in an integrated manner (something not usually done). Finally, it's (arguably) fun to read.
RE price: I would price the book less, but Amazon discounts the book like mad, so if I want to keep any semblance of respectability (i.e. above $20) I have to price it at $39. I also setup a 40% discount on lulu for today to match/beat the amazon discount.
I really want people to read the print version---it is so much better than the PDF, because you can flip through it, refer back to previous sections, and most-importantly the small size (5.5" x 8.5") makes the book look un-intimidating.