As you can probably guess from the name the Millennium controllers were initially launched as a celebration of the year 2000, a particularly wacky time were people were predicting the end of the world, Craig David was top of the UK music charts, and George Bush was elected president of the US!
Each colour was released separately and features the Millennium Edition logo on the controller itself. There are 4 flavours - Aqua blue, Smoke, Lime Green, and erm...Passion Pink). I'm almost certain that completes the Millennium set.
Millennium Clear Blue
The Clear Edition, seems to seems to be one of the rarer controllers out there as it was released towards the end of the consoles lifespan and has the text "2001 Winter, New Century" on the box. The box itself is fairly distinctive and is different to the traditional white boxes which most controllers, even the colour see-thru releases, used. The only ones which have a different box are the Dreamcast Direct colored editions which came in a drab, plain cardboard box. I'm not sure why the Clear Controller has a different box but if anyone has any further information please let me know.
Clear Edition Controller