The site was inspired by a site cartoonist Adam Koford (aka Apelad) put up -- Onomatopedia.com. On that site, Adam sells original cartoons inspired by onomatopedic words supplied by his customers. (I bought a cartoon of the word "poot".)
I like making funny sounds, so I thought it might be fun to do a similar thing with audio. The domains onomatopeia.com and onomatopoeic.com are held by a domain speculators or somesuch, but onomatopoetic is an acceptable alternate spelling and I liked the way that that it has "poetic" buried in there. Onomatopoetically describes how we're going to be saying these things and makes the domain name so long and difficult to spell that no one is ever going to be able to find the site*.
So the way it works is pretty simple. You suggest an onomatopoetic word (either a real one like "bark" or just some sort of sound spelled out) and if we like it, we'll record ourselves using it in a sentence and then post it on the site. It's likely to be pretty sporadic, so I suggest subscribing to our feed in your favorite feed reader.