Take an IP and try to look for the domain/host associated with it.
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Get all possible details about an SSL certificate.
Get all possible details about a domain name.
Ping a website, server or port..
Get the gravatar.com globally recognized avatar for any email.
Get & verify the meta tags of any website.
Easily convert bytes (B) to terabytes (TB).
Easily convert bytes (B) to kilobits (kbit).
Make sure your passwords are good enough.
Easily convert bytes (B) to yottabytes (YB).