I have a registration form, name, email, pass. I also offer the Facebook connection and in the future all other open id ways but for now i would focus on the regular process:
now i require the pass confirmation and then i send an email to confirm the email address.
but I really like also the Tumblr way, that doesn't require any confirmation but with your simple email+pass you are in in literally 30 seconds...
so my question is: someone know what is the best practice and in terms of metrics/stats if is better to allow an easy process but with the risk of high volume of fake,wrong,incomplete accounts OR ask more initially so those users who complete the process are "quality users"
i hope my question was clear, sorry for my English.