I'm just bouncing this idea around as I'm not quite sure how I'd go about it, but one thing that annoyed me when I started using drupal and that several friends have complained about as well, is actually finding the right module for the job.
We have reviews, and we have lists of similar modules and we have categories but for me at least, it still was quite difficult, and I think it might be a bit overwhelming for a beginner.
That's why I was thinking about some sort of recommender system. When you want to start building a new website you could tell it what you want the site to do and it would give you suggestions. Similarly it might work on already built websites, suggesting what other features might be useful.
I'm thinking it could aggregate a lot of the very valuable info already provided like ratings, similarities and categories of modules, but also do a bit of data mining and figure out which modules mesh well together, what are popular combination of modules and so on.
Perhaps it could even simplify the process of installing many linked modules.
Like I said, just an idea, any thoughts?