Minify your CSS by removing all the unnecessary characters.
Minify your JS by removing all the unnecessary characters.
Get all possible details about an SSL certificate.
Get all possible details about a domain name.
Extract email addresses from any kind of text content.
Get approximate IP details.
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.