Videos from the vault of the National Archives -- the public domain US government videos that public.resource.org have been scanning. Check out China's Great Leap Forward (the Beijing landscape has changed!), John James Audubon's Birds of America, and Nature's Half-Acre.
Browser Market Share -- fantastic circular visualisation of browser share over time. (via Mike Loukides)
NYT Year in Ideas -- some fantastic stuff, but I think my favourite is Zombie Attack Science.
dygraphs -- Javascript library that creates gorgeous zoomable graphs of timeseries data.

Tineye -- reverse search engine; you upload an image and they find you similar images so you know where else it's used. Check out their cool searches.
PDF Pirate -- upload a PDF and this web site will give it back to you minus the restrictions on copying/printing/etc.
Flare -- an ActionScript library for creating visualizations that run in the Adobe Flash Player. BSD-licensed, modelled on Prefuse. When there's a visualisation library for every platform, will we start to get people who know how to make them?
The Importance of Failure (Marco Tabini) -- This is a point that I don't often hear made when people talk about failure; the moral behind a failure-related story is usually about preventing it, or dealing with the aftermath, but not about the fact that sometimes things go bad despite your best efforts, and all the careful risk management and contingency planning won't keep you from going down in flames. This is important, because it forces every person to establish a risk threshold that they are willing to accept in every one of their life efforts.