The OSR in the title is the Old School Renaissance (or Revival, if you prefer) seems to be an internet driven 'thing' all about returning to the (possibly mythical or at least 'rose-tinted' nostalgic) roots of when roleplaying was done properly, as presided over by the Sainted Gygax himself. In practice, this has led to the creation of several 'retroclones' such as Labyrinth Lord and (my chosen iteration) Swords and Wizardry which are very careful rewordings of 'the original game' to avoid problems with copyright etc.
As with any 'ooh, shiny' moment, I've been spending a lot of time scouring the internet to find resources and (if I'm being honest) validate my choice of ruleset! So far, so good. I've also dragged at least one other into a dungeoneering party. So, a handful of the better links:
On avoiding the 'kill em all' approach fostered by video games:
Brilliant dungeon/city/everything map generator:
All round top blog with LOADS of idea:
The hilariously titled random hireling generator:
The S&W blog from the creators/publishers, Frog God Games:
An almost daily updated blog of spells, magic items, curses and the like: