Aside from "textbooks", there are quite a few more informally prepared lecture notes. Many of these are available online, but often aren't well advertised or easy to find, since they usually don't get published or make it to arxiv. I'll list a couple I know about (I attended some of these courses), and I'll wiki this answer so people can add more. The kinds of course notes I have in mind are ones that introduce or cover some big modern topic, rather than ones which are geared to proving one theorem.
Haynes Miller's course on Cobordism, (notes by Dan Christensen and Gerd Laures). An introduction to the Steenrod algebra, cobordism, formal groups, $MU$ and $BP$, and much more.
Haynes Miller, course on homotopy theory of the vector field problem, part 1 and part 2, (handwritten notes my Matt Ando). Covers classical topics related to the vector field problem, the EHP sequence, and Adams's work on Im(J). Somebody should TeX these These are available in incomplete form in a ..TeX document.
A couple of notes from courses by Mike Hopkins on elliptic cohomology and related stuff: 1995, 1999.
Jacob Lurie is currently teaching a course at Harvard about chromatic homotopy. He's posting his lecture notes, and Chris Schommer-Pries is also posting notes.
Anything else?