Another speech comedian was that guy from the 1970s, Ray Jay Johnson..... "You can call me Ray, and you can call me Jay... and you can call me...." Although he's been mentioned on The Simpsons, too, I'm really kind of surprised that in this retro/nostalga age of Jack in the Box back on the tube and Twinkie the Kid emblazoned on t-shirts that he hasn't popped up somewhere more recently.
Joe E. Ross had his "Ooo..oooo" of course. And although he wasn't a speech comedian really, Huntz Hall back in the days of the Bowery Boys shorts had his very distinct character, inculding his little whistle-and-point-with-his-thumb gimmick which I've seen copied in the occasional animated cartoon.
Going WAY back, and yes, courting a little controversy (hey, were all adults here) the Shorty the Barber character from the Amos and Andy radio show did a really good stuttering-sputtering routine. Racial issues and stutterer acceptance aside, good comedic timing is a rare and valued commodity.
Then there was the Fed Ex speed talker guy, who made a really healthy career out of that talent.
While by no means obscure, Chico Marx wasn't too much more than a dialect comedian (albeit one of the best) when his musical talents were't being engaged. More obscure was a dialect comedian named El Brendel, who always played funny talking, befuddled Swedish characters, although I don't think I've ever actully seen a film he's done. His catch phrase was "Yummpin' Yimminy!" - apparently, the "Wassup?!" of the day....