You must create or have an account at FamilySearch.org to participate. Accounts are free. I participate in keeping the data in their family tree accurate and well-documented. FamilySearch offers me free and extensive access to billions of records. Their goal seems to be to create one all-inclusive family tree, a goal I share and applaud. Their tools are world-class. Fortunately, my personal genealogical record-keeping software, RootsMagic, facilitates my connection to the FamilySearch Family Tree. Disclosure: FamilySearch is owned by the Church of Jesus Christ of Latter-Day Saints (of which I am not a member).
This is my WORKING database online at Rootsweb.com (no membership required). Although you can trust records in this database that are supported by good documentation, you should still check it yourself for accuracy. At Rootsweb.com you may download gedcoms of portions of this database (up to 10 generations in either direction) for use in your own genealogy application – for some ideas on which software to use, see my Resources page.
If you are an Ancestry member, you may find additional resources and links to documentation in my Ancestry database. Note: this database is not as current as my Rootsweb database.