Since there are so many "sql people" hanging around on this site, I thought I might as well mention about this one here..
I was taking an SQL course at school, and to make it slightly less boring for myself, I built, as the course project, an interactive SQL tutorial. It's available at http://iki.fi/sol/galaxql.html for windows, mac os x as well as source code that has compiled out of the box for at least some linux variants
The tutorial takes a slightly different approach than most of the SQL tutorials out there. You have a 3d, opengl-rendered galaxy, which you can manipulate using SQL. The virtual teacher explains SQL concepts with examples that you can try out, and gives tasks for you to figure out.
While I did try to make it as good as possible, it's bound to have some mistakes, but based on the mail I've received, there shouldn't be anything major..
The tutorial has received some positive reviews, and is, as far as I
know, in use in at least four universities in three countries. Quite
possibly more. Still can't get slashdot to post a news story about it, though.
And yes, I did receive "perfect" score from the course..