Convert text to binary 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.
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Get all possible details about a domain name.
Extract email addresses from any kind of text content.
Get all possible details about an SSL certificate.
Take an IP and try to look for the domain/host associated with it.
Make sure your passwords are good enough.