Illinois has a number of free databases that are searchable online including:
* Public Domain Land Tract Sales Database
* Database of Illinois Servitude and Emancipation Records

Databases of Illinois Veterans
o Database for the Illinois Veterans' History Project
o Database of Illinois War of 1812 Veterans
o Database of Illinois Winnebago War Veterans
o Database of Illinois Black Hawk War Veterans
o Database of Illinois Mexican War Veterans
o Illinois Civil War Muster and Descriptive Rolls Database
o Database of Illinois Civil War Veterans Serving in the U.S. Navy
o Database of Illinois Civil War Veterans of Missouri Units
o Database of Illinois Spanish–American War Veterans
o Database of the 1929 Illinois Roll of Honor
o Database of Illinois Soldiers' and Sailors' Home Residents

Illinois Statewide Vital Records Databases

* Illinois Statewide Marriage Index, 1763–1900
An Ongoing Project of the Illinois State Archives & the Illinois State Genealogical Society

* Illinois Statewide Death Index, Pre–1916
An Ongoing Project of the Illinois State Archives

* Illinois Statewide Death Index (1916–1950)
An index created by the Illinois Department of Public Health

* Records at Eastern Illinois University
o Arthur Local Registrar's Birth Certificates Index (1868–1925)
o Mattoon Death Certificate Registers Index (1899–1918)
o Mattoon Court of Common Pleas Case Files Index (1869–1873)
o Shelby County Circuit Court Case Files Index (1828–1871)
o Wayne County Coroner's Inquest Record Index (1888–1960)

* Records at Illinois State University
o DeWitt County Coroner's Inquest Files Index (1924–1977)
o Livingston County Probate Case Files Index (1837–1958)
o Logan County Circuit Court Criminal Case Files Index (1857–1945)
o McLean County Probate Record Index (1834–1934)
o McLean County Will Record Index (1838–1940)
o Vermilion County Coroner's Inquest Files Index (1908–1956)
o Woodford County Almshouse Registers Index (1868–1957)

* Records at Northeastern Illinois University
o Chicago City Council Proceedings Files, 1833–1871
o Cook County Coroner's Inquest Record Index, 1872–1911
o Chicago Police Department Homicide Record, 1870–1930

* Records at Northern Illinois University
o Carroll County Birth Certificates Index (1877–1913)
o JoDaviess County Almshouse Registers Index (1846–1938)
o Kane County Circuit Court Case Files Index (1836–1870)
o Lake County Circuit Court Case Files Index (1840–1898)
o Ogle County Almshouse Register Index (1878–1933)
o Ogle County Naturalization Papers (County Court) Index (1872–1906)

* Records at Southern Illinois University
o East St. Louis City Court Naturalization Papers Index (1874–1906)
o Madison County Probate Case Files Index (1813–1903)
o St. Clair County Circuit Court Chancery Case Files Index (1815–1870)
o St. Clair County Farm Board Record Index (1874–1879)

* Records at the University of Illinois at Springfield
o Macon County Circuit Court Case Files Index (1829–1861)
o Macoupin County Coroner's Inquest Files Index (1835–1928)
o Morgan County Poor Farm Records Index (1850–1932)
o Sangamon County Guardian's Case Files Index (1825–1901)
o Sangamon County Probate Case Files Index (1821–1885)

* Records at Western Illinois University
o Adams County Almshouse Register Index (1873–1898)
o Brown County Almshouse Registers Index (1882–1963)
o Fulton County Circuit Court Case Files Index (1825–1876)
o Mercer County Almshouse Register Index (1859–1948)
o Peoria County Probate Case Files Index (1825–1887)
o Rock Island Probate Case Files Index (1834–1899)
o Stark County Almshouse Register Index (1868–1941)

Deloris Williams

Take a look: