Once you begin following a few users on Twitter things can begin to get a bit messy, there is a solution which can tidy things up a bit, this feature is called “Twitter Lists’.
In affect “Twiiter Lists” allow you to group together people into relevant subcategories, therefore you could create a list called “colleagues”, by viewing this list you will filter-out all tweets from people who are not in your “colleagues” list.
Creating a list and adding people to these lists is extremely simple, also following users lists is extremely simple too, you can see full details on Mashable.
There are two sites I write for which use Twitter, these are ProductReviews and InEntertainment, I have set up a list which filters their tweets into a separate list, you can see the list here, you can also subscribe to this list aswell.
Also See: Ronnie Corbett tributes grace Twitter