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.
Check if the URL is banned and marked as safe/unsafe by Google.
Extract email addresses from any kind of text content.
Make sure your passwords are good enough.
Get the web-host of a given website.