I think he's just supposed to be some generic character representing the disgusting unfunny legions of webcomics out there but I think that's just my generalized hate of that genre talking.
As always,
IMDB is your best bet for finding out who's on a tv show. Here's the list though:
Spanky - Adam Corolla
Captain Hero - Jess Harnell
Ling-Ling - Abbey McBride
Xandir - Jack Plotnick
Toot/Clara - Tara Strong
Foxxy - Cree Summer
Wooldoor - James Arnold Taylor
I'm such a huge dork though that I recognized almost half the characters' voice actors as people from the Final Fantasy X games. Tara Strong voiced Rikku in both of them, James Arnold Taylor was Tidus in both, and Cree Summer was Belgemine in the first and Lenne in the second. Actually, aside from Abbey McBride, who apparently is an unknown, and Adam Corolla, who is known for being a tool, if you've played enough video games and/or watched enough cartoons you've probably heard these folks before. Jack Plotnick is another exception, he hasn't done any previous voiceover work according to IMDB and has just has a series of forgettable bit parts in various tv shows/films. I think it's funny that Jess Harnell also voiced Wakko Warner on Animaniacs. American voice acting circles are pretty incestuous though and you tend to see the same people over and over again *cough*CreeSummer*cough*.