The black keys of the piano produce two super useful scales, the major and minor pentatonics. These scales appear in just about every world culture and are incredibly ancient. They're nice for beginners because they contain no dissonant intervals, so it's impossible to play anything that sounds bad. By adding a note to the minor pentatonic scale, you get the blues scale, which is one of the cornerstones of blues, rock, jazz, country, R&B and much else.
Read more about pentatonic scales here:
http://www.ethanhein.com/wp/2010/the-pentatonic-box/
Read more about the blues here:
http://www.ethanhein.com/wp/2011/blues-basics/
http://www.ethanhein.com/wp/2011/the-blues-scale/
http://www.ethanhein.com/wp/2010/blue-notes/
http://www.ethanhein.com/wp/2014/blues-tonality/
