Plugins -- If it's not here, it probably doesn't exist. -- Yanfly is wonderful. Great technical plugins, and they're very easy to use. -- I love hime's plugins - I always seem to find just the one I needed. Great for those miscellaneous things that just make everything work better. -- Mog's plugins are flashy goodness. I'd say these are the most creative (and recreative:P) I've seen overall.

Obviously there are many more people making plugins. Great ones at that:D
But these are usually my go-to when looking for cool things.

Audio -- These cost money, but you can get some pretty good deals (still expensive though, rawr.)
I like them. They have decent to great music. I've yet to have problems with them. -- Decent to great music. I've had issues with them in terms of video strikes, but they have a huge selection.

You can also google "free rpg maker music" and find things.
Newgrounds is also a great site, if you're not going commercial. -- Has lots of free to use sound effects. -- Same^


i usually make my own graphics, but just googling "rpg maker whatever you're looking for" will help. Even if you're making your own, it's a great help for references. -- Costs money, but it's great for video effects.

Game Makers