Rational conformal field theories on elliptic curves yield
easily computable modular forms. This fact generalizes to higher genus.
Links:
[1] http://www.mpim-bonn.mpg.de/taxonomy/term/39
[2] http://www.mpim-bonn.mpg.de/node/3444
[3] http://www.mpim-bonn.mpg.de/node/5312
[4] http://www.mpim-bonn.mpg.de/node/5385