Additionally, if you have a Bachelor/Master degree in STEM, you can easily get a Blue Card if you receive a contract paying over 50,800 EUR/year. [1] Lower salaries would still enable you to obtain a regular work visa (which is specific to the job title and company).
I've heard Germany is a difficult country to establish a company (GmbH). I can't speak as an entrepreneur, but as an employee it isn't difficult at all to get a work visa from the government. I'd say the only difficulty is that you need to have every document prepared, with a spare copy, and make sure you've provided all the necessary information. German bureaucrats are especially irritable when things are missing/incomplete.
Germany is desperate for skilled workers. You don't even need to speak German to get a job in a big city like Berlin or Frankfurt.
As someone from North America, I'd highly recommend you consider Germany if you'd like to work for a start-up. Berlin is the start-up capital of Europe, and there are so many companies looking for talent you can quickly climb the corporate ladder/salary by moving companies every 12-18 months. You won't be paid as much as in Silicon Valley, but rents are sane and I'd say the quality of life is higher than in the US.
[0] http://www.make-it-in-germany.com/en/for-qualified-professio...
[1] http://www.bamf.de/EN/Infothek/FragenAntworten/BlaueKarteEU/...