There's also this - http://www.8thnote.eu/attenuator_details.html
Still, as time passes I'm starting to doubt if these types of attenuators are worth the hassle. To date the most elegant volume control I've used was digital as seen in the Sabre 9018 DAC's. My pipe dream to this day would be to use a digital volume control and build headamps without any of the expensive attenuators. The problem is that I've yet to found a ESS9018 based DAC that I would actually enjoy to listen to.
My favorite DAC chips from Asahi Kasei sort of have the digital volume control feature, but none really want to bother with designing a control board.
There are still interesting choices from BurrBrown and Muses but these also need control circuits that DIY people are reluctant to design.