Land records may not be on the top of your list of sources to search, buy they are among the most important sources for U.S. genealogy research. A large percentage of American ancestors owned land and even the earliest land records are of good quality. The most useful land documents for research purposes are deeds, which record the transfer of title from one party to another. A Grantor is the party selling the land and the Grantee is the one acquiring it. Deeds include relationship information, but also include valuable information such as place of residence and a land description.
Deeds often include conclusive genealogical information, the earliest deeds giving the most genealogical data. Names of wives are typically mentioned, but some other relationships are given, depending on local customs of the time. Deeds can document a transfer of land from father to son, usually without a fee or for a small one. I have found in my research that some men didn't bother with making a will and simply transferred the land in such manner to his offspring.
Migration problems can be solved through land records. For example, if an ancestor bought land in Ohio before moving from his New York home, the Ohio deed would mention his place of residence as Hometown, New York. The reverse is also possible. If an ancestor moved before selling his land, the deeds would record his residency as his new address. You can quickly see that land records can assist in tracking your ancestors, as some moved many times.
Land descriptions may also help you make connections. It is possible to trace a piece of land back through time. You might find that the land was given to your ancestor by his father, who bought it from a cousin, or whatever.
Land deeds are typically created at the county level and are indexed by both grantor (seller) and grantee (buyer). The Family History Library has a wealth of records, if you have access to that library. If not, contact the county offices of the place you are searching. You may want to reference The Handybook for Genealogists for information on the counties, the records they have, and their contact information. If legal terminology becomes a barrier, you can use references such as Black's Law Dictionary or A to Zax by Barbara Jean Evans for definitions.
