Are there any good tools that will keep track of my website's current registered and active users?

If your website offers registration, you should have a pretty good idea of the number of registered users. So I assume you instead want to know something else.

What website content managing software are you using, if any? (e.g., Wordpress) What “account” are your users registered to?

yep… please be more clear on your question… I can help you but you need to tell us what are you looking for?

Sorry for the lack of info.

my site requires registration. I can find out how many users I have signed up by checking the database but I guess I want to figure out how many users are “active” and I’m not sure how to do that. My site is not made with wordpress or any CMS like that. here it is if it helps: shootmap.com

If you have a record of the login times or the date last logged in for each user, you can count the number of users under a certain time threshold. For example, you can use this template for a SQL query.

SELECT Username FROM user_tbl WHERE Last_Login > DATE_SUB(NOW(), INTERVAL 10 DAY)

Or something like that.

Ok, to be able to do that you needed to add that script in the beginning of the website development. It’s easy, go back to your “form” site for registering and add an ‘active’ check mark that it will deactivate if the account doesn’t have any use for ‘x’ time period. The registered user will need to check that activation again when he enter next time and so on… Build a java script or an html/css one to do so.