Like many (most?) Internet users, I am an avid user of YouTube.
So #20 of the 23 Things was pretty easy: explore YouTube and blog about the features of the site that might be interesting if they were applied to library websites. I was also instructed to find a video that would make an interesting blog post.
What I like most about the design of YouTube.com is the site's extremely simple interface. After you select a video from your search results, a list of "Related Videos" appears on the side of the screen---making browsing very easy and rewarding. I think library websites are often too cluttered---they should look more like Youtube's website.
I found a video of a storytime event at the Rapid City Public Library by conducting a keyword search on the site. I think this is a great use of YouTube by a library: post videos of library events on YouTube and then embed these videos on the library's website.