Convert text to binary and the other way for any string input.
Convert text to hexadecimal 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.
Extract email addresses from any kind of text content.
Get approximate IP details.
Take an IP and try to look for the domain/host associated with it.
Make sure your passwords are good enough.
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Count the amount of characters and words of a given text.