I've just discovered another collected compiled version of early D&D available for free on the web. Steven J. Ege's The Gray Book is a collected, re-organized and slightly edited version of the OD&D rules and supplements (with some additions from The Strategic Review, The Dragon #1, Holmes D&D, Basic/Expert D&D, and even AD&D).
In spite of the additional material, The Gray Book has a house-ruled OD&D and supplements feel. The only major feature I noticed missing from OD&D and its three rules supplements is psionics. I could have easily used The Gray Book back in the late 1970s to run my OD&D games instead of OD&D, Greyhawk, Blackmoor, and Eldritch Wizardry.
Like the AD&D "3rd Edition" Books, The Grey Book is probably one big copyright violation. Grab your copy while you can. It's a free 4.2 meg pdf download and provides 146 pages of old school RPG goodness. If you would like to try OD&D with all the supplements, They Grey Book is a great way to do so without having to track down and buy the out of print original booklets.