Minify your HTML by removing all the unnecessary characters.
Minify your CSS by removing all the unnecessary characters.
Extract email addresses from any kind of text content.
Get approximate IP details.
Get all possible details about an SSL certificate.
Ping a website, server or port..
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Take an IP and try to look for the domain/host associated with it.