As yet I’m not allowed to publish an extension (I get: “Sorry, you are too new to add an extension to the repository. Please try posting it in our forum first.”), I share from here this simple account module hosted on GitHub:
It currently allows basic operations on an account: register, login, logout, account, change email, change password and desactivate. Next contributions could be: keep time and IP of registration and last activity, account verification by email and account administration.
I published this module under LGPL license, so you can use it freely but your improvements should keep de same free license. I hope to share in the near future new extensions like captcha, file uploader and wysiwyg editor widgets, file and article modules and so on.
Enjoy and share!