Animal Crossing: City Folk - Going to the Town Hall where you can usually have Phyllis or Pelly send letters and all that, you can also write letters to send to your Wii Message Board with or without a screenshot attached.
Bonsai Barber - When giving people haircuts, you can go to the menu with the scissors, gong, etc. and use the camera to take pictures and later send to your Wii Message Board. Also, customers can send postcards or the manager can send you complaints there...
Calling - You can take screenshots with your phone and send them to your Wii Message Board, or if you die in certain spots of the game you'll receive "death letters". Beating the game can also give you a "women in red". For more information, try finding a walkthrough for the game, those tell you where you can get these letters.
Check Mii Out Channel - (Discontinued) Opting in on the channel's newsletter would give you updates on your Wii Message Board about new contests. Occasionally you could take souvenir photos.
Dewy's Adventure - If you died on some of the game's boss battles, you would receive tips on your Wii Message Board explaining how to do better the next time you try to beat the boss.
Digicam Print Channel - (Discontinued) Purchasing one of the products offered gave you the option to send the receipt to the Wii Message Board.
Dr. Mario Online Rx - (Discontinued) When a friend sent you a Friend Battle Demo via WiiConnect24, it would tell you on your Wii Message Board.
Elebits - You could send screenshots at certain points of the game to your Wii Message Board.
Food Service - Purchasing some food with the channel gave you the option to send the receipt to your Wii Message Board.
Kirby's Epic Yarn - Any screenshots taken throughout the game and sent to the album, like in places found on the world map or in Kirby's Pad could be transferred to the Wii Message Board. It would also say where you took the photo on the message.
Kirby TV Channel - (Discontinued) Opting in on the channel's newsletter would give you updates on your Wii Message Board about new available Kirby TV episodes.
Mario Kart Wii - Playing all of the tracks would send you a souvenir photo with your Mii on it to your Wii Message Board. Also, this additional feature was discontinued, but you could also receive newsletters regarding competitions on Nintendo Wi-Fi Connection.
Metroid Prime 3: Corruption - Using the Screen-Shot Tool, you could send screenshots of your game to your Wii Message Board.
Metroid Prime Trilogy - Using the Screen-Shot Tool, you could send screenshots of your game to your Wii Message Board.
My Pokémon Ranch - Screenshots taken and kept in your album could also be sent to your Wii Message Board.
Nintendo Channel - (Discontinued) Opting in on the channel's newsletter would give you updates on your Wii Message Board about new games. Before the channel's "end of life", Nintendo also gave you the option to send all of your play logs and everything to your Wii Message Board.
Photo Channel - You can send photos from your SD Card to your Wii Message Board. Also, you can view all of your Wii Message Board's photos.
Pokémon Snap - Even though this is a N64 Virtual Console game, you can send screenshots to your Wii Message Board. As this has a few steps to it, please look at the operations guide for detailed instructions on how to post them.
Rabbids Lab - You can send screenshots of your Rabbids to your Wii Message Board.
Strong Bad's Cool Game for Attractive People - You are able to read various letters at different times send to you on your Wii Message Board.
Super Mario Galaxy - Beating the game and getting all 121 Stars would allow you to send a souvenir photo to your Wii Message Board. Collecting all 121 Stars unlocks a different picture if using Luigi instead of Mario, so there's 2 pictures in total.
Super Mario Galaxy 2 - You could send a souvenir photo with a list of Stars you got and everything to your Wii Message Board after you beat the game.
Super Smash Bros. Brawl - (Discontinued) Opting in to the game's newsletter would send you information on things such as new Snapshot Data.
Today and Tomorrow Channel - Periodically, the channel will send you letters to your Wii Message Board about your fortune.
Toki Tori - You can receive postcards from Toki Tori about his journey through the game as you play it to your Wii Message Board.
We Ski & Snowboard - On the main menu, there's an option to take pictures. Those pictures can be sent to your Wii Message Board.
Wii Fit - You can receive letters on your Wii Message Board about highlights of what happened during the day while playing Wii Fit.
Wii Fit Plus - You can receive letters on your Wii Message Board about highlights of what happened during the day while playing Wii Fit Plus.
Wii no Ma - (Discontinued) I'm not sure what this sent unfortunately...
Wii Party - You can receive letters on your Wii Message Board when registering a new Mii.
Wii Play - You can receive letters on your Wii Message Board when registering a new Mii.
Wii Sports - You can receive letters on your Wii Message Board when registering a new Mii, or you can receive letters about highlights of what happened during the day while playing Wii Sports.
Wii Sports Resort - You can receive letters on your Wii Message Board when registering a new Mii, or you can receive letters about highlights of what happened during the day while playing Wii Sports Resort.
Wii Shop Channel - (Discontinued) When you sent or received a gift with the Wii Shop Channel, you could receive letters on your Wii Message Board notifying you.
Wii Speak Channel - (Discontinued, but can still be done using Wiimmfi here.) You could send messages to your Wii Friends using your voice with Wii Speak, or/and you could send a photo from the Photo Channel from your Wii Message Board with it.
List of Functions that Used the Wii Message Board:
Announcements from Nintendo - Often, Nintendo would send you announcements regarding new things on your Wii in standby mode (Or in some games which use IOS35). Nintendo can still do this, but there's nothing new for them to send you...
E-Mail - You could receive e-mails to your Wii Message Board if someone sent you an e-mail if they registered you as a Wii Friend.
Posting a Memo - You can send a memo to your Wii Message Board with notes or whatever you'd like to say on it. This following part of it was discontinued, but you were also able to send these to your Wii Friends before WiiConnect24 was shut down.
Today's Accomplishments - Every Wii game, not counting GameCube games would automatically post how much time you've played the game for each day. If you sent a letter, it would be added as well.
We have all of the known sounds when opening the letter, the letter templates, and envelope icons sent to Wii Message Boards we extracted from games and channels on these corresponding pages:
Want to have a complete list of games that used the Wii Message Board? Or maybe you want to know what games allowed you to take screenshots to post on there? We have a complete list of games which do that, and how you could access it in the game!