Some weeks ago I added a Firefox search tool for Block Explorer to the Firefox addons site:https://addons.mozilla.org/firefox/addon/blockexplorer/
To me it seems like a useful tool to have, as you can search the blockchain on blockexplorer directly from Firefox without having to open the blockexplorer site first to enter your query.
However it appears that the reviewer was not convinced that this is a search tool of general usefulness to Firefox users, and as a result it didn't complete the full review, though it was accepted under a preliminary review instead. In order to get a full review it needs more users and more reviews, to show that there is a need for it amongst Firefox users.
If you think this can be useful for you, please try it, and if you liked it and have some time left, please post a review.