Chris Brogan has just written a very useful article about how performers can use technology to advance their careers, featuring the example of pianist Grace Nikae and her use of social media to connect with audiences. Some of the tools that Grace uses to build her brand are Twitter, MySpace, YouTube, and Facebook.
Grace Nikae's official website
Stretching Intervals, her insightful blog
Grace's MySpace page
Grace's Twitter page
Here she is playing an excerpt from Scriabin's Second Piano Sonata: