My new favorite thing ever, ever, ever.
It's an official and free archive of hundreds of streaming segments from Sesame Street, spanning it's entire 35+ year run. It's essentially a Sesame Street version of YouTube, and it's fantastic. You can organize the clips by character, which is great, because sometimes you get in the mood for a whole string of Bert and Ernie clips, or some great "Monty Python Junior" humor in the Grover-as-a-waiter skits.
Two downsides: you can't link directly to a video (otherwise, trust me, I'd have flooded you with recommendations by now), and there is no comment system. Though, the more you think about it, eliminating the comment system altogether is really the only way to keep the site entirely family-safe.
No idea how long they'll be able to keep this free and ad-less, so enjoy it now. And, I promise you, enjoy it you will. Anybody who thinks Sesame Street is just there to teach kids the alphabet clearly have no idea of why it was and is so successful.