Pre-packaged modules for use in rails projects ( blog, wiki, etc.)

Hi,

I'm brand new to RoR, so bear with me...

Note: If there is a document somewhere answering these questions already, feel free to simply post the URL with no explanation. I know it can be frustrating to answer the same question over and over.

I've been fooling around with RoR for a few days getting familiar with it. I really like it and I might switch to it for a project I've been working on in Java. I was using the JSR-168 portal standard, which was very nice because it was "easy" to include new snippets of functionality when necessary. So, I could add a blog portlet, a wiki portlet, etc. Also, there were many of these already made and I could just include them (theoretically...)

RoR seems much easier to develop in that slogging through all the nasty config files and whatnot. I've made my own (crappy) blog in order to prove that I could do it. Now, however, I'd like to get serious, and the first thing I'd like to do is grab as much free/open-source functionality that is already there, stuff like:

1. login 2. blog 3. wiki 4. user-role management (admin, user, permissions, etc.) 5. and many more...

So, my question is: how and where do I go to find pre-made RoR modules? How are they included? I've looked at plugins a bit, but they seem to be more programming related and not functionality related. The generators seem closer to what I'm looking for, but there are not many of them. It seems weird that there is not one (that I saw) for a simple blog or wiki.

Are there specific gems I should be using? If so, how does one go about integrating multiple gems into a single project?

Sorry if these are all simple questions, but I simply could not find an answer in searching the documentation.