Take an IP and try to look for the domain/host associated with it.
Get approximate IP details.
Get all possible details about an SSL certificate.
Get all possible details about a domain name.
Ping a website, server or port..
Extract email addresses from any kind of text content.
Convert forum type bbcode snippets to raw HTML code.
Convert markdown snippets to raw HTML code.
Find A, AAAA, CNAME, MX, NS, TXT, SOA DNS records of a host.
Validate JSON content and make it looks good.