I rely pretty heavily on the 'Widget Context' plugin (http://wordpress.org/extend/plugins/widget-context/), which allows me to show or hide widgets based on a number of criteria, and specifically I use the "target by URL" field. I use it because we have a network site of photographers, and the idea is that using Widget Context they can show an Widget that has a short bio, links, etc. on just their gallery posts, and then they can also have their own adsense codes in the widgets. Likewise, I use it to show ads on every page except for individual galleries.
As it turns out, that plugin doesn't work with Wordpress 3.3+ according to most users and the author, and for myself it works off and on. Is there an alternative or can one be created easily? I found the 'Widget Logic' plugin, but that doesn't allow me to target by URL. Any help would be much appreciated.