TwitterForBusyPeople (via @angryjohnny) is actually a great site! You enter your, or any, Twitter name into the single box on the homepage. From there it pulls the avatars of who posted in the last hour, in the last today and more than one day ago.
The idea being that many of the people you follow post so much content that they push the occasional poster way off of any page or client that you use. The idea of Twitter is living in the stream. Meaning seeing what is there at that time with some keywords available (al la Mixero). So you might miss items.
You can hover over any avatar and see the latest post from them, plus a small More link will expand the window to show a few more of their recent postings. If the pop-up has this little icon 
then it means there is a conversation around this tweet. You click that to get the conversation. Great work!
It will pull up to 500 of your friends, so if you follow more than that, then you need filters anyway.
Filed under: Add-on Tools, Web Clients, avatars, conversations, followers
Thanks for the review! We worked hard to make twitterforbusypeople.com fun and simple to use, while saving you time.
We do actually support more than 500 friends, but they become “paginated” – with 500 friends per page.
Thanks again – and be sure and watch for new features, as we have lots of plans!