  We present several new examples of nontrivial 4d N=1 superconformal field
theories. Some of these theories exhibit exotic global symmetries, including
non-simply laced groups (such as $F_4$). They are obtained by studying
threebrane probes in F-theory compactifications on elliptic Calabi-Yau
threefolds. The geometry of the compactification encodes in a simple way the
behavior of the gauge coupling and the K\"ahler potential on the Coulomb branch
of these theories.
