Once upon a time, one could download the CDDB, but I think since Gracenote took it over, you now have to license it from them to get a hard copy.

And then you're dependent on whether or not your ripping software will work with a local copy. The ripper would have to suport it that way, and I'm guessing most of them don't.

Personally, I'd just not worry about it and take the extra two minutes to type in the track titles. Seems to me that the total time you spend ripping and tagging while you're away from the internet would be less than the amount of hassle-time it would take getting a local copy of the CDDB working.