If you're in the OSR Discord channel, you've probably seen quite a few links to this recently, but I thought I would share it for those who aren't: Valzi / Michael Bacon is putting together a wiki for OSR house rules and variant rules. He's developed a standard submission format if you're interested in uploading your own. At the moment it's primarily Bacon's own material, interspersed with some of the better known works of Courtney Campbell, Skerples and Brendan S. and a handful of pieces by others.
Anyhow, I recommend people go add their own stuff to this, since I think a wiki-reference for all of the creative rules design work the OSR has done over the past ten years would be extremely useful. If you're not sure how, either reach out to Valzi at the OSR Discord channel or via his blog.