Gamasutra has an interesting piece up that celebrates the art of thoughtful thievery — based around the idea that there are "no new ideas," so picking and choosing your sources wisely can at least lead to interesting new creations. Going off the recent release of the 4th edition of Dungeons & Dragons, Tom Smith looks at a couple of areas where game designers could take some lessons:
Being inspired by concepts is not just a good idea. When your skill reaches a high enough level, it becomes a state of mind. Start by analyzing games in similar genres for good ideas. Dissect those ideas and learn from them. Then jump to similar games in different genres. Pen and paper role playing games and board games are a great next step.
A true epic-level master of concept-yoinking like Shigeru Miyamoto can take gameplay features from abstract activities like gardening. Pay attention to everything you see, from movies to conversations with friends to patterns in the ceiling tiles. Where do designers get the inspiration for new games? It's all thievery.
OK, I'm not sure it's fair to say it's all thievery (it sounds so bad!), but certainly there's a healthy dose of borrowing and reinterpretation. Anyways, even if you're not a tabletop nerd, it's worth a read through - there are some interesting ideas contained within.
The Adventurer's Guide to Thievery [Gamasutra]