Make sure your passwords are good enough.
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Extract email addresses from any kind of text content.
Ping a website, server or port..
Convert text to ascii and the other way for any string input.
Generate an MD4 hash for any string input.
Take an IP and try to look for the domain/host associated with it.