I'm running a Wordpress self hosted blog with registration and I would like to know if there is a safe way to know if users hasn't login yet or if account is unused by a long time. What I would like to achieve is to be able to automatically delete accounts that aren't unused by 6 months or more or not used at all. Any help? Thank you!
There's several plugins in the directory that will track the last login time of your users, each with various options: http://wordpress.org/extend/plugins/search.php?q=last+login
You could use one of those to track login times, and then delete unused accounts based on the information one of those plugins provides.