Minnesota Public Radio’s American Mavericks series is a collection of first-rate radio shows about American music. But it’s also a valuable website, the “latest attempt to find a home on the Internet for progressive classical music, which is played sparingly in concert and on the radio. “For Michael Tilson Thomas, the San Francisco Symphony’s music director and co-host of the “American Mavericks” radio series, the Internet is a logical place for young people to discover new music. Just as cutting-edge composers push beyond common assumptions, he said, a certain adventurous nature is needed to explore cyberspace.”