MaRS seems to be much bigger in science and medical startups, and unless you look for what they've been supporting it's like you mentioned most won't have heard of them because they aren't consumer facing. I think I mentioned elsewhere -- Shopify and 500px (I've applied there and failed lol) are some of the unicorns here. Good companies with good products and good talent. I'll have to check out AgileBits.

I work for a company that sometimes deals with other smaller startups but they can be fleeting in lifespan.

I would love to find something viable to join in on vs. the enterprise environment I find myself in now. Though I honestly haven't had my ear to the ground as much lately.