The Unh! Project: An Archive of Gutteral Moans
For all the OOFs and ARRGHs that characters utter in comics, there's the online archive called "The Unh! Project," which bills itself as "a collection of gutteral moans from comics."
The image to the left, of a dancer shouting "Ukh!" while being spanked by a little pig-tailed girl with a book, was the inspiration for the archive, which cross-indexes the sounds people make with the situations that cause them, e.g. "Being crushed by a giant python," or "unexpectedly falling in hole."
The creator has also put together some scholarly analysis of comic book vocalizations as well, if you want to get all technical about it.