With the overlapping characters, chances are very good that it's hand-lettered...

Hmm. I had hoped they simply did some layering of the text in Photoshop or something. Given the client and the budget they had at the time, I'm not sure they would have put that amount of effort into it. Argh! (of course, it would explain why my search has been unsuccesful thus far!) Thanks, oldnick! Any other suggestions would be welcome!

This is the closest I've been able to get so far using this sample:

Slappy
http://www.fonts.com/search/all-fonts?searchtext=Slappy#product_277822

Comic SCF
http://www.fonts.com/font/scholtz-fonts/comic-scf

Sluggo Black
http://www.myfonts.com/fonts/lillie/sluggo/black/

Handmade Bugler Solid
http://www.myfonts.com/fonts/breauhare/handmade-bugler/solid/

Those are awesome, Jared - especially the Slappy. So close it gives me hope that the exact match is out there! Will still keep looking - but if my search isn't more fruitful, at least now I have a back-up. Thank you sooo much!