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.
Take an IP and try to look for the domain/host associated with it.
Get approximate IP details.
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Make sure your passwords are good enough.
Get the gravatar.com globally recognized avatar for any email.
Get all possible details about a domain name.