Because I'm a public librarian, I will, from time to time, be harping on the value of the public library. When was the last time you checked out the database offerings at your local public library? What, you didn't know your library had online databases? I bet you didn't know it had a website either!
In the State of New Hampshire where the Write Sisters live, our state library makes databases available to public libraries. It saves librarians the hassle of searching for, and sampling services, and, it does the heavy-duty negotiating for a good price. Individual libraries may have even more databases than the state's offerings. Check out your library's website, or better yet, visit your library to pick up whatever passwords are needed! If you pay local taxes, you might as well use your local library! It's a great value for your money.
Here's what you'd find if you looked up the databases on my library's website: EBSCO, Biography Resource Center, Electric Library, Facts.com, NewsBank. These are the ones that I use personally. We have a bunch more, but I'm not much interested in business information or practicing for the SAT.
Now, if you don't have a public library that is operating in the 21st. century, then don't despair. If you graduated from a college or university, you may be allowed to use the databases as an alumna/alumnus. University offerings are fantastic! I envy anyone whose alma mater shares its resources!
If you write for the education market, don't forget about ERIC which is a free database service that deals with educational topics. There are plenty of government sites with information or digitized documents or other materials. One is the U.S. Census Bureau--it's great if you're working on a historic project.
If worse comes to worst, for a reasonable amount of money you can pay for a service such as NewspaperArchive. At around $100 a year, it's not bad if you do a lot of research in U.S. history of the past century. And, you may be able to write if off on your taxes! (Ask the IRS!)
By the way, please share any great databases that you come across. I look forward to hearing from you!