Get approximate IP details.
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Get all possible details about an SSL certificate.
Get all possible details about a domain name.
Ping a website, server or port..
Get the gravatar.com globally recognized avatar for any email.
Extract email addresses from any kind of text content.
Check if the URL is banned and marked as safe/unsafe by Google.
Make sure your passwords are good enough.