There already are questions about bookmarklets but are questions about browsers (plugins, features) accepted (as long as they are related to using a real web application?).
For example, questions about Greasemonkey, plugins to enhance a web apps' experience, Google Chrome's application shortcut feature, etc.
Personally I would say yes, but I'd like to know the community's point of view.
Note: This could go in the FAQ (as on or off-topic depending on the result).
Example of such a question: What are the most useful plugins for Gmail?