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.
Use the Google translator API to generate text to speech audio.
Decode Base64 input to an image.
Convert forum type bbcode snippets to raw HTML code.
Convert text to binary and the other way for any string input.