I have added a simple DCM model renderer script called dcm2dot to my SPM Hacks page. With this function DCM model files (DCMxxx.mat) will be analysed and their network written out as Graphviz .dot files. You then can use graphviz small programs like dot to render the network to PNG, PDF, SVG, etc.
Here a simple example of a V1-MT+ DCM:

I have added a short script that will estimate all available DCM models within a directory to my SPM Hacks page. This is a simple way to get parallel DCM Model estimation without a dedicated PC cluster and works also with multiple PCs if you put the files on a network file system. Note however that matlab uses one licence per user per PC, so you may run out of licences fast. But if you have a 8 core Linux PC you may be able to estimate 8 models at the same time in 8 matlab sessions using just one licence.