Barbie.com
playable on Flashpoint + NumukiThis was THE site of all time to 7-year-old me. I have so many fond memories of giving Barbie blue eyeshadow, accessorizing her pets, choreographing skating performances, finding her shoes, and so much more. Barbie.com peaked in its pre-Flash days, but was especially best around 2003-2008!
MyScene
playable on Flashpoint + NumukiMyScene was technically a spin-off line of Barbies, but it had its own microsite. I played these games over and over. The shopping spree (above) was my favorite, but I also loved the makeover and room design games. MyScene's city-girl contemporary 00s style was so iconic!
Poptropica
Online but limited; full version on FlashpointPoptropica is an online adventure game where players solve quests with historical and cultural tie-ins. I remembered a lot of the quests being quite difficult, and playing them genuinely strengthened my dexterity and problem-solving skills. I started playing Poptropica in 2007 when it launched, and though I don't play it anymore, I do have access to my old account from 2007! Unfortunately the end of Adobe Flash ruined the game, so most of its features and islands disappeared. The old version is still accessible by downloading Flashpoint though!
Build-a-Bearville
defunct :(Oh man, I miss this one so much. It was basically a virtual Build-a-Bear Workshop community, featuring a designable character you could name. Players could enter a code from the store bought bear's certificate, which would add them to the virtual game! Bearville was more wholesome and positive than other multiplayer sites. An unofficial team is trying to rebuild the old game and I'm hoping they will!
Polyvore
defunctPolyvore was basically a digital collage maker for fashion enthusiasts. Unfortunately, it's no longer running. Platforms like URStyle and Pinterest Shuffles are modern replacements, but they're used for more general collage-making than fashion planning.
Club Penguin
defunct but fan-made servers existI didn't play Club Penguin super often, mainly because gameplay was limited without purchasing a Membership. I explored some of the fan-run servers (see the Club Penguin subreddit) to scratch my nostalgic itch, but I'm not a huge fan of them.
Disney Channel
playable on disney--games.comMy favorite games were all the Lilo & Stitch and Kim Possible games. disneychannel.com had a lot of cool tie-ins with the station itself: anyone else remember voting for the cameo appearance in High School Musical 2?
PBS Kids
playable on Flashpoint and NumukiThis site had games for several educational TV shows but Arthur was my favorite section! The games were fun but also taught problem solving, phonics, and critical thinking.