Convert text to hexadecimal and the other way for any string input.
Convert text to ascii and the other way for any string input.
Convert text to decimal and the other way for any string input.
Convert text to octal and the other way for any string input.
Ping a website, server or port..
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Get approximate IP details.
Get all possible details about a domain name.
Make sure your passwords are good enough.
Check if the URL is cached or not by Google.