Extension:SubpageWatchlist

The SubpageWatchlist extension does adds on option to the Special:Watchlist navigation, so that in addition to things on your watchlist that were recently edited appearing, it also adds any subpages of watched items that were recently edited.

This extension has not had its performance evaluated. It should be fine for a small wiki and probably even a medium sized wiki. Given that watchlists are already a somewhat scary query, I feel like this shouldn't make things that much worse (although it does make things not as good). One probably would definitely not want to install this on a Wikipedia sized wiki without doing some good performance analysis and testing.

Known issues: If you're watching Foo and Foo/bar, and someone edits Foo/bar, the extension will make it appear on the list twice (Once for itself, and once as subpage of Foo). This extension considers all pages with a / to be subpages, even if subpages aren't enabled in the relavent namespace.

Installation
Use patch or something to apply the following diff in your extension directory (Hey I did mark this as experimental). Too lazy to get a git repo.

Otherwise, standard install instructions -