Web Application Development?
jaddison: Use a framework that handles user accounts/passwords for you.  Twitter, Facebook and other social auth frameworks can be plugged in easily via 3rd party modules.I use and recommend Django, for example.  I would imagine Ruby/Rails would have similar capabilities.For Django tutorials/docs:
http://docs.djangoproject.com/en/1.1/Django is also about to release a major update in the first half of March (v1.2).  Some GREAT improvements.