For some people, parallel computing and the need for a cluster is a way of life. For others, the need sneaks up on them. Most clusters and grids are planned and organized from the first, and that can take time and effort, to say nothing of configuration. Other times there's no budget for new hardware, but there are computer labs or desktop computers unused for much of the day---a cluster waiting to be harnessed, if only you can get the Macs to talk to the Windows boxes, and keep straight all the hostnames in use. For situations like these I helped develop Wolfram Lightweight Grid System, which is designed from the ground up to let you assemble existing hardware into a self-organized network, accessible from Mathematica with almost no configuration.
Computation & Analysis