Free Online Games
50 States: http://pivotentertainment.com/50states or http://pivotentertainment.com/50states2
Take a blank map of the US 50 States and place the states puzzle style into their correct locations. It sounds simple, but you may find you don't know as much about the locations of the 50 states as you think.

There is also a 50 States version 2. This one plays the same, but it uses a satellite map in which to place the states instead of a plain US outline map.

Arcademicskillbuilder site: http://arcademicskillbuilders.com/
There is large variety of educational video games that offer an innovative approach to teaching basic academic skills by incorporating features of arcade games and educational practices into fun online games that will motivate, intrigue, and teach your students.

Play games for free right on the site! No need to download and install!

Guess the Google: http://grant.robinson.name/projects/guess-the-google/
This is one that you may need to try to appreciate. Guess The Google presents a collage of 20 images that were retrieved from a single Google image search. Your job is to guess the search term.

Guess the Google is more fun and addictive than it sounds. You have 20 seconds for each group of images and can guess as many times as you can in that 20 seconds. You get a score based on how quickly you come up with the correct answer. Some of the groups of images are easy to guess and some are more difficult. This would be a good game to play when teaching Internet searching.
 
Magic Pen: http://nutstation.com/Game/MagicPen/MagicPenFlash.swf

The object of the Magic Pen game is pretty simple. You need to touch all the flags on a level with a ball. The interesting and fun part of the game is that you need to draw all the parts you use to solve each level. You are given a crayon as your drawing tool.
You can draw circles and (almost) free form shapes. You can draw pins to attach one drawn piece to another in a static configuration and hinges to allow pieces to pivot. The amount of creativity you can use to solve some of the more difficult levels is almost unlimited.
Here are a few hints to keep in mind.
• The eraser is your friend. It is not only for correcting mistakes.
• Triangles make good wedges.
• Remember that you can place pins and hinges on the ball.
• The whole thing is based on physics.

Dots: http://wildstyledesign.com/dots
This is not your grandmother's dots game where you connect dots with a pencil. This is a wild adrenaline pumping action game that will keep you on your toes. You must hit the red dots that give you points and the yellow power-up dots while avoiding the evil purple dots that kill you.

Soccer Juggle: http://wildstyledesign.com/soccer
Soccer Juggle is very simple. You just need to click your mouse to keep the soccer ball in the air. It sounds easy, but it requires good eye hand coordination and good timing.

Bubbles: http://wildstyledesign.com/bubbles
Bubbles is a variation of Samegame with some very nice features. If you turn on highlighting and set the mode to "shifter" it makes the higher levels a little easier to win. A word of warning -- this, and the other Samegame versions, can be very addicting.

Shuffle: http://shockwave.com/content/shuffle/sis/shuffle.swf
The object of Shuffle is to knock your opponents balls off the table while keeping as many of your balls on the table as possible. The game visuals are very colorful and attractive. The game play makes for an addicting and fun time waster.
Each game consists of a number of rounds. The first play to win four rounds wins the game. Each time you win a round you get less balls for the next round. This keeps the game very challenging. You always get the first shot and that is usually and advantage if played well. You get extra points for knocking out more than one ball at a time. You get points for every ball you have left of the table at the end of a round.

The games are pretty short, but Shuffle is one of those games that you always just want to play one more time and before you know it an hour or two has passed and you still want to play just one more time.

Mahjongg: http://freebies.about.com/od/onlinegames/qt/mahjongg.htm

There are many Mahjongg games around the Net, but I particularly enjoy this one by Thomas Weibel. It is written entirely in DHTML and should work with any browser and operating system. After the page is fully loaded you can even continue playing if you disconnect from the Internet.

There are quite a few options you can set with the buttons at the bottom of the page. You can change from the traditional tile set to one with playing cards. If the display is too small for your taste you can click on the zoom button and play with a much larger board.

Try different tile layouts -like the one that is a simple 8x9 square and two tiles high. It is more challenging than it first appears.

If you get stuck and can't find a move you can use the hint button to show you an available move. If you just want to know how many possible moves there are you can click on the moves button. If you need information on how to play the game just click on the help button.

Totem Destroyer: http://armorgames.com/files/games/totem-destroyer-1871.swf
The object of Totem Destroyer is to explode a prescribed number of stacked blocks without letting the golden idol hit the ground. The early levels are easy, but it gets more interesting as the levels progress. It is a physics based game and you need to think about what each move will do. You need to plan ahead to have a safe place for the idol to land.