Rated 5 out of 5 stars
I have to write again and say that Captain Caveman (aka Martjin) is awesome! I asked a question on 07/20/09 - or 09/07/20 if you live outside of the US - about adding opacity settings for the tabs. I hadn't heard anything for a day or so when, out of the blue, arrives in my inbox an extension attached to an e-mail.
Captain Caveman had sent me an updated version of his extension and asked me to play around with it to see what I thought. After playing with the settings for about an hour, I wrote him back and told him that it was exactly what I was looking for. The updated extension makes it easier than ever to distinguish the active tab from the background tabs (if you don't want to turn off the extension's effects on background tabs). Plus, if you really play around with the settings, you can come up with some very interesting tab colors.
I think there's a lot of intelligence written into the way the extension determines its colors for the tab AND the text on the tab. For example, if the tab is very dark, the extension will change the text from black to white so it will remain clearly visible.
It's a great extension. I'm using it in conjunction with TMP (turned off the tab and tab text coloration features) so I can keep the tab behaviors I like. No conflicts noticed so far!