This is the 500 pages long briefing document prepared by the Disclosure project led by dr. Steven Greer. Enourmous amout of evidence, events and interviews with insiders. A must get for everyone.

Disclosure.Project.Briefing.Document.(500.Pages.Of.Solid.Ufo.Evidence).(2001).pdf

A shorter executive summary version (100 pages):

Disclosure.Project.Briefing.Document.-.Executive.Summary.(solid.UFO.Evidence).(2001).zip

Also of interest are the MJ12 PDF documents from www.majesticdocuments.com site (visit for download). Quoting from the website: Majestic Documents.com is a groundbreaking look at the United States UFO program called Majestic and the top secret government documents that tell the story of presidential and military action, authorization, and cover-up regarding UFOs and their alien occupants. A remarkable work of investigative journalism, this website is the first to authenticate top secret UFO documents that tell a detailed story of the crashed discs, alien bodies, presidential briefings, and superb secrecy. Special attention is paid to the forensic authentication issues of content, provenance, type, style and chronology. The story the documents tell leaves the reader with little doubt that the cover-up is real, shocking, and at times unethical.
Here are some of the most interesting ones:

MJ12.files.-.Analytical.report.about.flying.saucers.pdf
MJ12.files.-.Bowen.-.Encyclopaedia.of.flying.saucers.pdf
MJ12.files.-.Eisenhower.briefing.pdf
MJ12.files.-.German.scientists.linked.to.MJ12.pdf
MJ12.files.-.Important.memo.pdf
MJ12.files.-.Interplanetary.phenomenon.unit.report.(Roswell).pdf
MJ12.files.-.Isotope.thermal.thrusters.pdf
MJ12.files.-.Jane.Crain.-.Official.docs.pdf
MJ12.files.-.Jane.Crain.interview.pdf
MJ12.files.-.Jehovah.pdf
MJ12.files.-.MJ12.5th.annual.report.pdf
MJ12.files.-.Relationships.with.inhabitants.of.celestial.bodies.pdf
MJ12.files.-.S-aircraft.pdf
MJ12.files.-.Teller.-.Pitch.for.SDI.pdf
MJ12.files.-.Teller.-.UFO.technology.and.the.imbalance.of.power.pdf
MJ12.files.-.Twining.-.White.hot.report.pdf
MJ12.files.-.UFO.Linked.Military.Personnel.Data.pdf
MJ12.files.-.UFO.sovereignty.over.air.space.pdf