I'd be interested in an RSS feed for questions with at least a certain number of votes or replies. This might be implemented as a GET parameter appended to any feed URL.
For example, the following feed might return PHP articles with at least 20 votes: stackoverflow.com/feeds/tag/php?v=20
The following feed might return jQuery articles with at least 15 replies: stackoverflow.com/feeds/tag/jquery?r=20
This would purposely reduce the list of PHP articles for users interested in reading, but not necessarily replying to, specific topics.