Please say it ain't so!!! Rated 5 out of 5 stars
"NOTE: Won't be updated to work on Firefox 3, due to changes in how tabs are rendered."
If ColorfulTabs can do it, I would think it's certainly possible to get ChromaTabs working.
This is the first Add-on I install when putting firefox on a new machine. If the technical hurdle is true, this add-on will certainly be missed.