This is a good article with links for open source products. The author did a good job of summarizing the products.
Not every proprietary program can drive a person crazy, right? Some, like Norton Ghost, are superb tools for anyone to use. But, the fact that these tools are proprietary can drive open source fanatics up a wall. It’s not the price of the software that makes the real difference (although it’s a reason to migrate from one software to another for many people); it’s the idea that proprietary software comes with boundaries that keeps the user experience confined to…well, being the user. That’s enough to drive any developer crazy.