[lukev]

Using a language that supports an interactive development library might speed up the process for you.

I use Clojure, and like Incanter for this kind of work. I also use Datomic as my data store, when I can, which makes it quite easy to perform ad-hoc queries.

Of course, the fact that your data is too large to effectively fit in memory means that, whatever you're graphing, you're going to have to aggregate it a bit first before you can visualize it. That's really the hardest part of what you asking, and how you do that efficiently depends entirely on what your query is and what kind of data store you're using.

I'm not aware of any off-the-shelf software that does what you're talking about, unless it fits into an OLAP-type schema (http://en.wikipedia.org/wiki/OLAP_cube) for which there are several products available.