While I was in Vienna for a music festival this July, I became more aware of the use of Viennese Tuning (A1,D,F#,A). This tuning system for the double bass was used during the Classical Period predominantly in the Austro-German lands.
Igor Pecevski's Viennese Tuning resource:
Thanks to Igor Pecevski, there is a good online resource to learn more on Viennese Tuning for the double bass. According to the materials listed under the section "The history of the Viennase tuning", "it is believed that this tuning system originated in the Baroque period at the time when the period bassists have started emulating the Baroque lute and viol tunings."
The Viennese Tuning is ideal for playing works in the key of D major and the closely related tonalities (e.g. B minor, A major and F# minor). However, it can be difficult to play works in other keys (e.g. Eb major) using the Viennese Tuning. Perhaps this was the reason why Viennese Tuning did not achieve universal acceptance eventually?
For more information on Viennese Tuning, please refer to this useful resource by Igor Pecevski: http://viennesetuning.com
This resource contains introduction on this subject, and it also offers useful introductory materials on the fingering basics of the Viennese Bass Method. The page also offers encouragements for anyone who would have the courage to learn the Viennese tuning. Furthermore, the webpage offers a series of information on teachers and institutions that offer instruction related to Viennese Tuning.
Rinat Ibragimov's discussion on Viennese Tuning:
For the visual learners, there is a YouTube video of Rinat Ibragimov on Viennese Tuning. In this video, Rinat Ibragimov discussed the practice of Viennese Tuning on the double bass. He has made particular reference to the concertos of Vanhal and Ditters von Dittersdorf. The video can be found here: http://www.youtube.com/watch?v=xGd2hgfhUrA