Cladistics would probably have remained an obscure scientific methodology had it not been for its appropriation by dinosaur-loving paleo geeks the world (and world wide web) over. A simple google image search will return hundreds of hits. Historically, dinosaur cladistics derives from a seminal paper by Jacques Gauthier (Gauthier (1986)); more recently, other professional paleontolgists such as Tom Holtz have helped popularise and explain the subject.
Here we also need to distinguish between cladograms proper, which are diagrammatic representations of phylogenetic hypotheses, in which each terminal node represents a species, and dendrograms which are more generic tree-like diagrams, in which terminals include supra-specific taxa, species and higher ranks are combined, and/or a number of cladograms are mashed together. Unfortunately, these two terms are almost always conflated, even by professionals.
The above dendrogram shows the cladistic relationship of the dinosaurs, from Holtz's GEOL 104 Dinosaurs: A Natural History course notes (see Rise of the Dinosaurs). Each of the major clades are also illustrated by one or two silouettes and skeletal illustrations a la Greg Paul (where two illustrations are shown, the lower one is the more basal). The phylogenetic position of Eoraptor (and the Herrerasaurs) is uncertain; we have suggested here that the Herrerasaurs constitute a paraphyletic assemblage of early forms. See also UK Dinosaurs for a dinosaur supertree, dated 2001, thus predating the first peer review published supertree (Pisani et al (2002)). There uis also an updated version in both circular and stratigraphic format.
Mickey Mortimer (The Theropod Database) has created an amateur a giant ascii dendrogram of the theropods and a somewhat smaller one of the Sauropodomorpha, inspired by Mike Keesey's much missed Dinosauricon site. while the the Open Dinosaur Project gives a 2010 cladogram of selected basal archosaurs, dinosauromorphs (protodinosaurs), basal saurischia, and ornithischia. General comments, with hyperlinked taxa, can be found on Wikipedia (along with a basic bubble diagram version). MAK120206