Either a ajax or even a basic search should be implemented in the backend of Joomla. There are a few extensions for this which I use one, but this is something that should be built into the backend. This would help newbies as well as hard core developers with finding articles, modules, menu items, and plugins. I'm sure it would help a lot of people to have this addition.
This actually came up a few times during J & Beyond. I know we discussed it during the Search Working Group session (theoretically, we could tie the Smart Search data into a backend search without having to use even more resources, for example), and I know a few people were talking about it elsewhere. It's definitely something that's on everyone's minds to accomplish, just hasn't really been worked on just yet.