I note the recent article on Open Source investment. I was too late to make any useful comments there, so I thought I'd put them in my diary.
Strangely, a growing proportion of my income is from Open Source development, or based on Open Source software. If I have a client that wants a job done, I look around for suitable open source tools. Last year it was PfaEdit (which I still use) and this year it was the swish-e search engine. In each case the product did not quite match my client's needs, but I was able to modify the source to get the functionality I needed - and then contribute the new code back to the project - I would not even dream of trying that with a large commercial software company. The end result is a happy client, improved open source products and an income for me.