I was first introduced to this dish (or should I say dishes?) by stumbling across Quong's page on the subject. (Here's an archive in case it goes away.) This was in the late 1990s when I was travelling every other week to Mountain View, California. I managed to try most of the places then on Quong's list before I stopped flying west all the time.
Dan dan mein is a confusing topic. First of all, it's really two different dishes that deserve to have two different names. Sometimes it's warm noodles served in a moderately spicy peanut butter (and/or sesame paste?) sauce, which I will call Taiwan style. Other times it's warm noodles served with ground pork in an extremely hot sauce that doesn't taste at all like peanuts, which I will call Sichuan style. Both styles are quite tasty.
(Are my Taiwan/Sichuan labels valid? I don't know. Go find a food anthropologist to ask and let me know, but until then I haven't been able to come up with anything better.)
Then there's the name. Dan Dan Mein, Dan Dan Noodles, Dan-Dan Mein, Dan-Dan Noodles, Dandan Mein, Dandan Noodles, Tan Tan Mein, Tan Tan Noodles, Tan-Tan Mein, Tan-Tan Noodles, Tantan Mein, Tantan Noodles, Dun Dun Mein, Dun Dun Noodles, sometimes also Dan Dan Mian, plus descriptive names in English such as Noodles with Hot Meat Sauce (for Sichuan style), and literal translations such as Carrying Pole Noodles. It's just plain confusing. My personal preference seems to be Dan Dan Mein.
擔擔面 (also common)
担担麺 Japanese, or sometimes 坦々麺