Current favorite is Rammstein World.
https://www.rammsteinworld.com/forum/ If you speak French (or have a good translation program) I highly recommend it. I've followed it for a while now; if r/Rammstein is the kids table, then Rammstein World is where the grownups eat. The commentary (especially on Till and Richard) can be blisteringly blunt. The admin Pierrick also created Lindemann World for Till/Lindemann band-specific topics.
The Rammstein Belgium Facebook site is good for news, posts are in English. They were a good source of information about the birthday concert debacle Till (rightfully) got grief about.