How Has Open Source Helped You Commercially?

Slithe asks: "In the past few years, OSS has proven that sharing one's source code can be beneficial to both businesses and their customers. More than a few young programmers are thankful that they were allowed to learn from professional developers by browsing through and hacking on 'enterprise quality' code. My question to developers of commercial OSS is this: Have you, personally, ever benefited from having the source code to your project freely available and dowloadable, instead of being kept under lock-and-key? Have you ever fixed a bug in your spare time? Have you ever sought outside help (providing source code snippets) on a particularly nasty problem?"