Take an IP and try to look for the domain/host associated with it.
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Get approximate IP details.
Get all possible details about an SSL certificate.
Ping a website, server or port..
Easily convert IDN to Punnycode and back.
Extract email addresses from any kind of text content.
Make sure your passwords are good enough.