Humble has hooked up with Goodman Games to release an RPG Bundle Deal that nets a pretty substantial amount of book content.
The sale runs for the next 21 days and includes a treasure trove of The Dungeon Crawl Classic RPGs.
All are DRM free and in PDF format
$1 unlocks 12 RPGs
$8 or more unlocks 14 more
$15 unlocks 20 more
around 50 RPGs for that price? Steal.
A particular favorite is The Emerald Enchanter ( Dungeon Crawl Classics #69)