weka.clusterers
Interfaces 
Clusterer
DensityBasedClusterer
NumberOfClustersRequestable
UpdateableClusterer
Classes 
AbstractClusterer
AbstractDensityBasedClusterer
CheckClusterer
CLOPE
ClusterEvaluation
Cobweb
DBScan
EM
FarthestFirst
FilteredClusterer
MakeDensityBasedClusterer
OPTICS
RandomizableClusterer
RandomizableDensityBasedClusterer
RandomizableSingleClustererEnhancer
sIB
SimpleKMeans
SingleClustererEnhancer
XMeans