AdServe seems like an excellent plug-in, but it still has some major potential for growth...
HTML-based ads are pretty much a must-have feature. Links in the HTML could easily be auto-detected and prepended with a PHP file to count the number of clicks (e.g.
http://www.whatever.com would become
http://www.wordpresssite.com/adserve.php?clicktracker=http://www.whatever.com ) OR users could simply prepend their links with a
%%ADSERVE%% marker, which AdServe would then replace with the PHP prepend. (There should also be an option to disable auto link detection)
Auto-detecting zones throughout WordPress would be a fantastic feature, if not a huge one-up on larger packages like phpAdsNew/OpenAds. Users could place the
[!AdServe:zone!] tokens in their pages/posts, and then select which zones each ad goes to from a list with checkboxes.
One other feature AdServe could use would be something of an 'inventory management' system, where users specify a "capacity" or maximum amount of ads that can use a single zone, to ensure that one zone isn't showing too many ads and spreading impressions too thinly between them. (i.e. 'Zone 4' has a capacity of 3, and is full once ads A, B, and C are set to rotate through 'Zone 4')
Those are pretty much my only thoughts for now - I wish I were more fluent in PHP to give a hand with development.
A sincere thanks to the author for creating & keeping up with this plug-in!