Twitter rolled out lists to everyone today. The thing I'm most excited about is the ability to follow all of the Security Twits with a single click. I already follow quite a few of them, probably more than half, since I primarily use Twitter for security news and interacting with people of that mindset. SecurityTwits also created lists for Security Companies, Blogs & Research (of which HiR is included), Media, and Events.HiR even has a list of our authors!
You are able to make lists to share with others, too. All of the Twitter accounts from your local 2600 group or hackerspace, your fantasy football pals, or comedy troupe, for example. Also, like SecurityTwits, there are already a bunch of public Twitter lists out there that you might be interested in following. Mashable has a good catalog of lists started.
Related: Roll your own hive-mind