Users of PrintableFlashCards.net have each other to thank for the batch of 15 new flash cards. Categories vary and span everything from math and geography to Greek gods and the endocrine system.

"One of the things I really enjoy about this site is seeing what everyone comes up with," said Kevin Savetz, the site's creator. "Of course, PrintableFlashCards.net has the most popular stuff such as multiplication flash cards, but there's also topics like Albert Einstein facts and Ojibwe vocabulary."

All of the printable flash cards are organized into categories such as language, science, literature, childhood education and math. Some of the new additions include medical prefixes and types of teeth.

There are 148 flash cards available for free as PDFs. They can be downloaded and printed from a home computer. People who prefer to create their own flash cards can use the flash card maker, which allows users to put either four or six answers to a page and share their knowledge with others.

"If users can't find what they're looking for on the site, I highly encourage them to use the flash card maker," Savetz said. "Their cards may get shared on PrintableFlashCards.net and helpful other site users."

There are more than 80 sites in the FreePrintable.net family of free printables sites created by Savetz Publishing, Inc., a company devoted to creating useful and informative web sites of interest to consumers and small businesses.