Topic: Best Gem For Various Jobs?

I had this posted somewhere else but I didn't see this sub forum so I'm re-posting (deleted the original) to get input here regrading the various gem discoveries people have made

There are a lot of gems, that's what makes working on rails excellent is all the available gems.  I'm still a beginner but I have plans so I've been exploring trying to find the right gems for what I want to do - but 'organization' isn't exactly out there in the open source world - at least clean organization that I've found.  GitHub is the great repository but people don't always describe their projects in a clear way.

For instance, it took some time because i'm helping a friend out and she needs file uploads - and i found paperclip - but I know that I need gems (if they exist) for the following tasks

1.  Blog Comments (preferably THREADED comments - I prefer the threaded comment functionality - if it had ajax updating that would be awesome too), single author is ok multiple authors preferred
2.  WYSIWYG plugin (as part of the blog system would be excellent - if not - just a WYSIWYG editor itself)
3.  E-Commerce plug ins - I see many of them out there.

4. Manufacturing Interface - now I know this one might not exist - but if it doesn't - I'd love to work on something like this with someone - I'm in manufacturing (food) and think rails provides a perfect framework for building a GOOD inexpensive system