Tag Central was created in 2005 as part of Godlikenerd.com. I created it after noticing that 43 Things imported data from other services that are tagged with the same thing. This site aggregates this data from a variety of sources. All one needs to do is provide a keyword that the data should be labeled with.
I moved it to its own domain soon thereafter. Peter Parkes adapted Jon Hicks' Del.icio.us Makeover to the site and it was made the default theme thereafter.
And that's how it became the site you see today.
Great way to look up tags,check out your most used tags,reverse search tools.