My first was The Big Enchilada which I came across via a google search for, I believe, Mr. Horsepower and for some reason that came up. I was heading for a two hour car ride, downloaded a few episodes, and upon returning back home downloaded the rest of them.
Next up was Way Past Cool and You Got Good Taste. Ever since then, these have been my 'go-to' podcasts and sources for great music. Of course I would be remiss in failing to mention Sonic Nightmare. However, it was TBE that made me look at my record collection and say, I have to fucking do this.