I'll be participating in Swords & Wizardry Appreciation Day on April 17. S&W was my intro into the wacky, wild world of the OSR when I returned to the hobby a few years ago.
I'm not exactly sure what I'll be posting, but rest assured that it will be as gonzo as my usual content-heavy posts.
If you haven't done it yet, be sure to check out the free online d20 S&W SRD.
S&W comes in three flavors: Complete, Core, and WhiteBox.
Complete will cost you some cash, but the other two are available as free PDFs. You can download the Core rules for free here, and the WhiteBox rules for free here. There's also a support site with some free downloads here.
There's an active Google+ community here.
There's a forum that needs some loving here.
Finally, be sure to check out Mythmere's blog for more resources (and if you want to see some really old stuff of Mythmere's check out his old C&C site on Tripod.com!).
And this is also an excuse to yet again post my favorite RPG cover image from the WhiteBox 2nd printing: