Wizards.com/hottub
The website Wizards.com/hottub comes from the card Urza's Hot Tub printed in Unhinged. Like the card says, you are basically tutoring by discarding one card and searching your library for a card the contains an exact word from the discarded card. This can be any word in the discarded word's name. This website helps you to search through a database for cards with a single word from as many words as you type in. The results are displayed and from there selecing a card takes you to the Gatherer, which is the official Magic: The Gathering card database.