There is a free trial version of the materials in the National Library of virtual manipulatives. Math topics Numbers and Operations, Algebra, Geometry, Measurement and Data Analysis & Probablity are covered. I did not come across anything asking for money so I a not certain there is a cost. There are tons of manipulatives to access from each of the above categories. This site is associated with the Uta State University.
This activity is a scaffolded process of working users through the understanding of fractions beginning with how to divide up an item through the creation of fractions. Would be a good IWB activity.
Grammar Ninja is a fun game for students to play as they develop a working knowledge of the parts of speech. Grammar Ninja has three levels for students to work through. As long as you answer questions correctly, they continue through the game, but answer incorrectly and the words explode.
Ghost Blasters is designed to help students learn to multiply and divide quickly in their heads. To play Ghost Blasters select a multiple of which each "bad" ghost will have a value that is a multiple of that which you chose. Students then use their mouse to blast every "bad" ghost. For example, if I select "5" at the beginning then all bad ghosts will display a multiple of 5. I then have to blast all of the bad ghosts to gain points, but if I blast a "good" ghost (a ghost that does not have a multiple of 5) I lose points.
PBS Kids Cyberchase website offers forty-five educational games for students in third through fifth grade. The games are intended to help students develop their skills in mathematics, logic, and pattern recognition. Students who have PBS Kids accounts can keep track of the games they've played and rank the games they've played.
Fling the Teacher is a website containing 68 history quiz games. All of the quizzes have at least fifteen questions and a few of the games have more than 100 questions. The average is 30-45 questions per quiz. Prior to starting each quiz game students can create their own custom game character.