Media centre Boxee lets you access a lot of web video sources, but what about that clip your friend emailed you earlier today? Boxqueue is a bookmarklet/webapp combo that feeds bookmarked clips into your Boxee feed.
It's a clever and mostly elegant little hack, playing off the simplicity of an "Add to Boxqueue" bookmark bar button and Boxee's RSS versatility. After signing into Boxqueue and adding a personalised feed to your Boxee account, you're halfway there. After that, you simply find a clip you want to watch through your (likely TV-connected) Boxee setup later, hit the bookmarklet, and when you're in Boxee, head to the "My Feeds" section to see a queue of items you've saved for later.
Free to use, works with most any streaming video site, and requires a sign-in with your Google and Boxee accounts to activate.