I've just started with Moodle and I'm impressed by a lot of its features but one erally important thing's missing: an advanced search capability. Right now as I understand it there is the ability to search different parts of the environment, but now way to do an advanced search. Let's say, for example, that a student wants to search both the forums and glossaries (FAQ) and everything else on the site they have access to. Like me, for example. I was looking for where to post a "feature request" and I ended up doing two searches - one in "FAQ" and one in "forums". I'd like to search the documentation, as well. And any courses I have access to, too.
I'd say this is a very important feature that's missing from moodle.