Free online tutorials. I like this one, because (a) it is okay for self-paced instruction and (b) it provides a way to track progress.
"Thousands of video lectures from the world's top scholars." This general area I think is where the Internet shines -- the gift economy at its best. A rising tide lifts all boats. Give and it shall be given unto you...
Although the site looks to be based in Taiwan, the video lectures are in English, and I like this one because it uses a Calculus text that I already own. The link is specifically to an intro Calculus course, but more courses are available from the site.
From the New York Time -- covers different types of online education opportunities.
Large collection on online learning materials, including open source textbooks.
"Open source educational software is rapidly gaining adoption in a wide array of teaching environments." List of open source apps by function and what apps they replace.