Crowdfunder allows you to invest in companies for a share of future returns. Unlike rewards based crowdfunding, you are investing in the future of a company as a stakeholder. Once you are accepted you can browse through the deals available and choose the ones that match your investment profile. They have projects in industries ranging from aerospace to real estate.
Crowdfunder currently requires you to be an accredited investor according to SEC rules in order to be able to invest in the projects listed on their website, which means earning over $200,000 over the last two years or having over a million in assets. This is expected to change in the future however to allow smaller investors to participate in new deals so keep checking the website.