Electrotank have just released a new version of their multiuser XML socket server ElectroServer 3.

For up to 20 concurrent users it's free. For more users the price range goes from US$299 for up to 50 users up to US$2999 for unlimited users.

Here are a few features:

• Server-side ActionScript support
  
• Server-side plug-in support (to enhance functionality, good for real-time
  games)
  
• Database support
  
• ElectroServer ActionScript class for Flash MX or Flash MX 2004
  
• Language filter
  
• Zone support (groups of rooms)
  
• Many other features that make multiplayer gaming easier