We need to have the slashdot comment archives available through a good search engine. It should be able to identify comment topic, even if it does not match the article topic. It should be able to distinguish some amount of accuracy, most likely through moderation levels and types (though that has accuracy problems itself). The searcher can even search for funny vs informative (or even troll if they so desire).
Once results are returned, the searcher could browse through the comment tree normally and search out related comments, parent or child. It would allow the searcher one more layer to judge the usefullness or accuracy of the results.
This is a bit more in depth than just googling over slashdot. It needs to take slashdot comment relationships, user comments across articles, and moderation into account when grading results. Google alone cannot do that. It sounds like a tough job, but it would be a great resource for slashdots parent/owner. Maybe they could be convenced to take the plunge.