View history would actually be pretty easy to implement at the moment with the map caching. All the files are stored in the map directory
<game id>-<game turn number>-<phase id>[-smallmap][-<md5 hash of game password, if it's protected>].png
The way I'd like to get it working is with four small 'start', 'backward', 'forward', 'end' icons below the map in board.php (like in a video player), that could change the map being viewed using JavaScript
http://phpdiplomacy.net/doc/history.jpg
It'd have to get a list of the maps in the current game that are in the directory, enter them into a list in a generated javascript, and let the user change the src of the map to one of the maps in the array by clicking the buttons
If someone wants to have a crack at this that'd be great (
[email protected] for dev.phpdiplomacy.net details), otherwise I'll get around to this eventually