Great! Vic also come up with some good references
I'm thinking to categorize by 3 aspects
1) By tag (by information content)
Posts are automatically tagged by the contents.
These are feeds, not permanent bookmarks, so I see no point of manually tagging it either.
2) By source (mmgeeks? mmitpro? etc.)
3) By author (ThetThwe? victorlin_21? )
That means even if you write in multiple sites, if you still stick to same user name, all your posts shall be under your name.
Tag Cloud: I'm not sure now useful it would be in our case because the tags you see are automatically generated, not user generated.