r/askhistorians is a very professional, academic forum.
For more popular discussion of history, see Reddit - Dive into anything. Most threads there are as good as the posts we have here at the SDope.
And if you’re feeling sad, be sure to look at Reddit - Dive into anything, or /www.reddit.com/r/aww.
Almost everything on reddit is well written,with good grammar, and a friendly atmosphere.The problem is that it’s just too big and impersonal.
It’s like fishing–you can drop your hook in, and pull out something interesting. But It’s harder to post there, and much harder to have longer, back-and-forth debate.
(And never use capital letters if you type the URL in your browser…It’s the only website I’ve ever seen that doesn’t work with caps )
That link is nsfw. Well, I guess it is safe… if you’re ok with your cow-orkers seeing you all teary-eyed and such. Thank you for sharing MadeMeSmile; it is a gem.
I hit the xda-developers forums from time to time for the Android-ish devices I use. There are general ones but the ones for certain device families attract my attention.
While I mainly use them for things like rooting a device, how to tweak a rooted device, etc. There are often subforums where people talk about their favorite apps, how to do interesting things, accessories, etc.
Along these lines is the TiVo Community. Lots of TiVo and dvr related stuff. But I only go there in search of specific info: How to do X? How do fix problem Y? etc.
One forum I’ve visited a few times recently is this xkcd-based one. Seem like good folk, but just a few people making a few posts.