Y8.com or y3.com or gamesbox.com and/or miniclip.com
kids world
http://www.kiddieskingdom.info/
Webkinz and Poptropica are some good sites
Some good website game sites could include:coffeebreakarcade.comminiclip.comaddictinggames.comflashgames247.comnewgrounds.comarmorgames.comflash-games.net
some good kid web sites are... moviestarplanet.com animaljam.com and roblox.com
Here are some good kids' websites that I know of: clubpenguin.com disneychannel.com marapets.com moshimonsters.com nickelodeon.com pbskids.org whyville.com
My fave website is fantage
Usually online poker sites are not the best place for children. I suggest you find a game in the basement of a brothel to take your kids to.
Webkinz.com, babydow.com, pixiehollow.com, superpokepets.com, and howrse.com are all good Web sites for kids.
There's a heavily filtered roleplaying forum on moshimonsters.com. Some kids roleplay on sites like Animal Jam and Toontown, but they aren't as active. There's a good roleplay forum on kidzworld.com.
Ponybox is a great sim/RPG game
One can find a good review for kids online games on the games site themselves. Most online game websites for kids will have a section where you can read feedback about different games and sites. You can also use yahoo answers to look at some thoughts people have on different online kids games.