Michael Shorten known as Chgowiz has done a great job with the Swords & Wizardry Old School Reference Sheets which you can find here.
They have some character gen stuff, spell listings, and a complete monster reference. Along with a nice treasure generation set of tables that is very complete.
Now I admit these type of products are not exactly the most exciting thing in the world. But when I started doing Wild North I quickly photocopied, scanned and pasted together a set of reference sheet. Looking through the rulebook for this stuff is a pain. This is also coupled with the fact that not every chart in the books need to be duplicated. There are some that you will rarely use if ever.
When I looked through what Chgowiz did I was impressed that he made many of the same choices as I did. I feel that this product will be of useful practical benefit both in creating characters and in the referee creating stuff for his game.
So if you use Swords & Wizardry you can't go wrong with this product.