The following packages are known to depend on or use graphviz:
Requires
webdot
doxygen
R
ImageMagick
anjuta
Require - but just use dot's stdin/stdout simplisticly
perl-GraphViz
perl-Graph-Writer-GraphViz
perl-Graph-SocialMap
rpmDirectoryCheck,
k3d
BuildRequires only (doxygen, graphviz)
libxml++
icu
taglib
koffice
bakery
cppunit
jrtplib
libburn
QuantLib
rapidsvn