If there’s a fine example of rapid prototyping and game development out there, this has to be it. Big Hadron Games caught our attention from a recent postmortem on Game Career Guide which outlined their pains and gains from making a whole bunch of Flash games in a really short time with a pretty small team.
This project includes some Global Game Jam entries like For Shame and Treelings, which aren’t half bad considering that they were made in 48 hours. We strongly recommend that you actually play through a few of their games before checking out the postmortem.
If you want a brief overview of why prototyping is good for you (and all that other stuff), there’s an article over on NAG Online that you may want to look at.