Today is the coldest day of the year so far. How do we know? - because my teeth are chattering and because someone keeps track of all those records on a database. Many disciplines use databases; last month I listed some for music. Database information is often a bit more tricky to locate because they do not appear as regular web pages that a search engine might access.
To help with this problem, try http://library.albany.edu/internet/engines.html#deep
Here you will find a collection of sites that specialize in finding information from the "Invisible Web."
An example: Using the http://www.invisible-web.net/ site and looking in the public records section, I found the Department of Health Restaurant Inspection Database (NYC, Boston, Denver, LA) where you can check to see who has been listed for violations. I bookmarked NYC (-:
Locating a good database is becoming easier; finding interesting and relevant lessons that use these databases for more than simple information retrieval is the challenge.
Here we have the Art ImageBase from SF Fine Art Museums - http://www.thinker.org/fam/subpage.asp?subpagekey=70 searchable and you can create your own "gallery" and the Metropolitan Museum of Art - searchable, create your own gallery - http://www.metmuseum.org/. The lesson plan (http://historymatters.gmu.edu/d/6875/) is aimed at the Met but the idea could easily be adapted for the SF site or another art database.
The NY Times maintains a wonderful database of lesson plans (http://www.nytimes.com/learning/teachers/lessons/archive.html) and because the actual URL was far too long, I suggest that you type in the keyword "database" and then select the subject and grade. I used "Language Arts", 9-12 and found 9 great lessons that ranged from creating a database to help with missing persons, another one on the topic of National Identity cards, one on Iceland's genetic pool, and one on Justice Harry Blackmun with links to the databases on law and Supreme Court decisions.

Other related sites and ideas:
• Lesson Plan - Humanities - Uses database of images, Native American culture - http://historymatters.gmu.edu/d/54/
• The Perseus Project from Tufts - http://www.perseus.tufts.edu/
From this site you can head to various databases on Papyri, Greek vases, the Renaissance, etc., etc. One of the site's best features is the Tool area where I found the Atlas Tool. I typed in "Rome" to search for all the cities in the world that had "Rome" and found one of my favorites, City of Rome Dark Swamp. You can then zoom in and in and in to learn that City of Rome Dark Swamp is located in Pennsylvania, not far from us!
• http://ebbs.english.vt.edu/medieval/medieval.databases.html a collection of Medieval Databases: Chaucer, music, poetry, the Vulgate, etc.
• http://lcweb2.loc.gov/ammem/ndlpedu/lessons/constitu/conintro.html
• http://www.gliah.uh.edu/historyonline/lesson_pl.cfm Classroom-tested Lesson Plans and Handouts Created by Master Teachers