Installing Adsense on the archive pages
 

Either edit the index.php file (in the archive folder) or just make a plug-in at hook location archive_navigation (or where ever you want them to be) to echo it out so you don't have to change the index.php file on an upgrade.

If its for vBulletin you can have a look at:
http://www.vbulletin.org/forum/showthread.php?t=100299