Italian composer and arranger Giovanni Dettori based his "Lady Gaga Fugue" on her 2009 hit "Bad Romance." In this video, his friend Vincenzo Culotta plays his neo-Baroque piece on the piano. Dettori writes, "To give a "modern feeling" I used a special treatment of fourths, fifths, suspensions and rythm [sic]."
Ok, full disclosure: this video was posted on YouTube way back in April 2011 and was a big hit back then apparently. It was the first time I had seen it though. I enjoyed it and figured many of you would too.
Incidentally, just this year, the original video for "Bad Romance" surpassed 1 billion views.