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There's wefunder too (https://wefunder.com/) who are getting set up to allow unaccredited (lower net worth) investors once the JOBS act goes through.

I was just going to mention Seedrs: http://www.seedrs.com/invest

(among many others but they seem to be the most popular choice in the UK)

You have RockThePost as well https://rockthepost.com where they connect investors with early stage tech startups