I will kick this off.  As discussed in the developer forum a photo competition module would be a fantastic addition to the site.

After reading again the threads and the thread on the ability to upload an image to the site here are my thoughts:

Users can submit only 1 image per month for the competition. 

The monthly competition has a theme.  this could be heritage month, main line, coal etc.

Once a user has submitted their image which must be on the railpage DAMS the image is then tagged as entered.

A user cannot submit the same image for a comp more than once every 6 months.

There is an RSS feed for the monthly competition which is syndicated to the internet.  probably the facebook page Railpage has and maybe twitter

users who enter the competition are advised by notification of other users submissions. This is by way of email announcement.

Submissions are open for the month with voting starrting at the commencement of the month and ending on the last day of the month.

Once images are entered voting for images commences.  As more photos are entered more images to vote on.  this will ensure users get their images in early.

Users who submit into the competition enter a league table. This league table is an ongoing table which lists the most voted images in the competition across all months.

users cannot see the number of votes per image until the end of the monthly voting and the winner announced.

users cannot vote on their own image.