I like the photos at airnav,but cant enlarge.
Any other sites have airfield photo's?
To be sure of your intent, are you referring to the still pictures of airports AirNav sometimes will have for airports under the "Aerial Photo" section of AirNav?
If so, most times those photos are sent to AirNav by volunteer members of the site and I believe they are purposely reduced to make the page load faster. I am not sure if the AirNav site operator would be responsive to a request for the original picture, but you may want to try. You also may want to send him a request asking him to enhance his site by allowing a user to click on the photo to see the larger picture. That would be a cool site enhancement.
Another idea is to search
Airliners.net as their photos come in three of four larger sizes. No idea if they have airport photos there but it is worth a look.
BogMan - You're welcome. I meant to state that I am not aware of a comparable non-US site. Hopefully someone else here with that info will chime in.