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 approximate IP details.
Get all possible details about a domain name.
Ping a website, server or port..
Extract email addresses from any kind of text content.
Get the gravatar.com globally recognized avatar for any email.
Get all possible details about an SSL certificate.
Check if the URL is banned and marked as safe/unsafe by Google.