Earphone jack cover

Given the problem you've noted, I'm surprised that no one has made something like this as yet; at least I've found nothing on Google. I've tried the plastic top off a Bic Biro pen, and it works pretty well, but you have to whittle down the plastic so that it fits snugly. You might try the same if you have no luck elsewhere?
Cheers.

Message was edited by: jia10

I have not seen a stand alone cap but I can suggest the iskin revo case it has a headphone jack port plug on it....

also

here are instructions to make your own
http://www.instructables.com/id/Apple-IPhone-Headphone-Jack-Plug/

hope this solves your issue

i use the iskin case and it has a little flap that goes over it

I have an otterbox defender case and it has covers for the earphone port and the dock port.

nope, don't think they make a stand alone cap. maybe you can be the first one to invent it and become rich! but mhornet18 is right, I've got the otterbox case and it does protect the whole iphone from dust and dirt (plus many other things).