ZUBB also comes with a fairly adequate search engine, which lets you search for messages either by subject or body. This search engine is accessible via the ZUBB function menu at the top of every page.
This search engine returns a list of posts matching the search term, ordered by date (not thread). Users can then select individual posts to read them, and reply to them if required.
In addition to this, ZUBB also features a fairly cool function named "New Posts" - this provides a list of all the newest messages posted to the board, regardless of which message thread they belong to. This is a quick and useful way of seeing all the new messages that users have added to the board since your last visit, especially if you're a frequent visitor.