Date the photo was taken.

Also, the main camera settings can be useful, e.g. shutter speed, aperture, ISO.

Some people may prefer not to have this information displayed with their own photos, perhaps they told their wife they were going somewhere else that day, but that could be controlled by an option in account settings.

Same than Dan :-) + Original image size.......    The link on fotopedia at the top fleft is perfect except than today it link to magazine pages and it seems to be difficult to browse out except using the link to our profile.

The magazine is excellent!  The best way to have index is to use flipboard on Ipad ! It's really nice.... I didn't find index on Safari.

I completely agree with Jean-Michel: the size of the original image is an essential information. Before voting for a photo, I always make sure that its dimensions conform to the Fotopedia quality charter on this criterion. And I have often rejected with regret a picture I found yet very beautiful, but whose size was not appropriate. Conversely, I also voted in favor of images that seemed to miss some sharpness, but whose extreme dimensions could explain that feeling distorted by the display format proposed.
Other desirable information: the date of the shooting, the title of the image (which can sometimes be helpful to evaluate the relevance of the photo on the topic of the article) and a commentary by the author, when it exists.

@Jean-Laurent: The new design is good but it needs maybe to increase the minimum size of pictures. Less than 1620x 1080 is not enough.

800x533 or 533x800 is now a small size.

Portrait pictures are also not very easy for display.

Commentary on each picture is a goal for me, English is not always easy to do it.

I agree with all the above mentionned items: date taken, camera settings, image size, title and author comments (if any)

Possibly, something could be done with the latitude/longitude co-ordinates, if they exist in the photo's EXIF data.