Olympics: If your cable tv company is participating, you can watch live streams of the events online

on nbc olympics website. It worked really well in 2012/2014; they streamed pretty much everything, including preliminary rounds, through to the finals. (They do not live stream the opening/closing ceremonies though.) You need to use a sign-in from your cable company (one that you get if you register on their website, not your email account with them.)

As an example, this is day 1's stream page:
http://www.nbcolympics.com/live-stream-schedule?day=1

Scroll down past the video offerings to the schedule section, which is in bright green. Click on the '>>' to the right of a sport's title. When the streaming page loads, I think it will provide you with information on using the feature if you haven't signed into it before.

One caveat, you need to either allow 'third party cookies' in the browser you use to watch the streams, or list your cable company's url, such as 'rcn.com' and the nbcolympics.com as exceptions to third-party cookie blocking. If you use a browser like chrome, where the settings page has a search function, searching for 'third' should quickly bring you to the detail setting. (Generally speaking, it's best to disallow third party cookies, so you might want to change that back when you're done streaming, if you're not using the exception method.)