While bioinformatics tools for the analysis of DNA sequences, reaction kinetics models of biomolecular networks and molecular dynamics simulations of biomolecules are all widely used, multi-cell modeling of developmental processes (including tumor growth) at the tissue scale is still relatively undeveloped. A key reason for this neglect has been the lack of widely-accepted modeling approaches and the computational difficulty of building such models. Now, a growing community of modelers has settled on the GGH Model (also known as the CPM) as a convenient methodology to create multi-cell simulations of tissues. I will present sample simulations of the front instabilities of a simple "toy" model of growing avascular tumor spheroids and some slightly more sophisticated models of tumor vascularization to illustrate the capabilities and limitations of the GGH model as implemented in the open-source modeling environment CompuCell3D (see www.compucell3d.org).