User/Account web service (.NET)

I want to build 开发者_运维百科an web service in .NET that should handle basic user/account management. The initial interface should include (but might be extended in the future):

• CreateUser
  • Create a user with information such as Email, Name, Adress etc.
• UpdateUser
  • Update the user account information
• GetAssociatedData
  • Get data associated with this user

I could build this myself using by having the web service talk with the database, but I was wondering if there's any nice technology out there to manage accounts like this? There might even be something in .NET? If not, what should I consider when building it myself?

The users are arbitary users that doesn't belong to any windows domain or such.

You can use the SqlMembershipProvider with aspnet_regsql.exe as a starting point and extends it to support custom data associated with the user.