So, the more I looked the more I found OSR RPGs that use Swords & Wizardry as their core (as well as RPGs that used other clones as their core, and a whole boatload of clones and derived systems.) A whole lotta games.
Where did I find such a listing?
Never heard of it? Neither had I. But my, it is a site of link goodness for clones and derived games of ALL editions of D&D. Yes, even 4th.
It includes a list of 16 RPGs that are built upon the Swords & Wizardry Rules and 3 built off of the Labyrinth Lord rules
Then there are the clones built directly off of OD&D, Basic and AD&D 1e and 2e. About 60 or so. not including the games listed at the end that branch off a bit further but still have solid roots in D&D mechanics.
There is a lot to dig through, some of which is totally new to me.
I'll be cherry picking some of the free ones for the final parts of the first section of the OSR for the Lapsed Gamer series of posts, but I see no reason why one couldn't jump ahead and find a gem or two on their own.