This may sound weird and you are like, "whats the use of this anyway?
If you don't want to setup any Database system and you just want a quick login to your ArcGIS and you want the user to feel confidant without specifying any password, you can simply Authenticate her with her Own Twitter Account!
I built this Extension with VB.NET for ESRI ArcGIS. When you start the GIS it simply start a Login Form and ask you to login to Twitter using oAuth (no password there)
When you login, I return a class filled with the most important information about the Twitter User, Name,ScreenName,Location and picture where you can easily use to customize.
I've also placed a sample button to tweet. You can easily build your own client based on this, like when someone Edited a feature you can use his Twitter Account to log on his name details.
I just know that someone will make use of this one day, so I thought I just develop it.
Download the script here.