The Bayreuth Festspielhaus still performs nothing BUT Wagner to this day, but they only seem to perform versions with heavily altered sets and costumes- turning Gods into men in suits, turning mystical caves into factories and turning the depths of the Rhine into a hydraulic dam. It's extremely difficult to find performances of Wagner's Ring that stay true to the original.
Following is the performance of Levine at the Metropolitan Opera house of 1990. The Metroplotan Opera house of course can't compare with the Bayreuth Festspielhaus which was specifically designed by Wagner himself to perform his Operas, but as opposed to the artists at the Festspielhaus nowadays, the Metropolitan Opera House is at least trying to perform Wagner the way it was meant to be performed.
If anyone knows of older versions (preferably from the time before the Bayreuth Festspielhaus began to modernize it's performances and preferably old enough to be in public domain) then please link them. Die Walküre has English subtitles - the others do not. So if you have trouble understanding German or (like me) ARE German, but still have trouble understanding what they are singing, here is the entire Libretto of Wagner's Ring as PDF files in German and English: http://home.earthlink.net/~markdlew/shw/Ring.htm