I found the machinima forum on the SecondLife Community page this morning. I have been around SL awhile but I admit I've never read the forums and blogs closely. So this is probably not a new-to-you resource, but it was to me.
People advertise/announce their machinima projects on the site. There are some posts about tools to use. And users have some posts looking for cast and crew for their projects in case you want to get started by helping on other people's projects or you have the acting bug. So looks like it might be useful on a couple of different levels.
Some assorted links