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..
Generate passwords with custom length and custom settings.
Check if the URL is cached or not by Google.
Make sure your passwords are good enough.
Take an IP and try to look for the domain/host associated with it.