Feedly is one of my favorite examples of "small company in the right place at the right time." They had an RSS reader website that was, in most respects, exactly like Google Reader. They also supported easily importing Google Reader subscriptions.

The day Google Reader announced it was going away, me and everyone else found Feedly and said "hey, this is basically the same thing and I can switch easily" and bam, they grew like crazy.

Literally a half million users showed up on Feedly in 2 days. http://blog.feedly.com/priorities-keeping-the-site-up-and-ad...