Learnivore is a new(ish) site by 
French Rubyist Thibaut Barrère that aims to aggregate all of the best screencasts in any easy to navigate, searchable manner. Learnivore is worth following (you can even follow it on Twitter) because unlike blog posts, screencasts from disparate sources haven't really been specifically indexed and presented well before.
Currently, Learnivore has a very strong Ruby and Rails focus though it's not exclusively Ruby - there are some Web design and iPhone videos mixed in there (though mostly still of interest to the average Rubyist, IMHO). The sources are BDDCasts, EnvyCasts, New Relic, SitePoint, Peepcode, Railscasts, RubyPulse, and the Pragmatic Programmers - all Ruby-leaning sources.
Naturally, Learnivore isn't the only Ruby screencast aggregator in town - RubyTu.be is another new-ish site in the same niche, though Learnivore takes the presentation crown in my opinion. Two great resources nonetheless.
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