Yes, just open this course picker in several browser windows or tabs. They operate independently from one another.
We couldn't scrape all the data for all courses. You can help us scrape the data out of the official course catalogue and we'll incorporate that data into this application. Yes, you can help ease the pain of thousands of students. Let us know if you want to help and we'll tell you how.
In Firefox 2.0:
We have tested on Firefox 2.0 on Windows and MacOS X, and Safari 3 on MacOS X.