I see why you like them so much. Zeeks offers at least a hundred games. You can choose from board games, arcade games, card games, brain teasers, puzzles, gadgets, mindless fun, plus games for math, science, and language arts. I really like this site. It lists which browsers and versions each game works with and what plug-ins are required.
Every game also has a help page with instructions and a page of reviews by kids.
I like seeing what other players think, and if the reviews are positive I am more likely to persevere trying to play a game. To find which games you'd like to play, you can sort them by popularity and subject, and see the five most popular games. If you like arcade games Kiddonet is another good site to visit. I've only tried a few games here but there are lots to choose from, such as speed-testing games, sports games, board games, holiday games, and thinking games. Kiddonet Jr. offers early learning games for younger children.