Online thesaurus help?

I lost my bookmarks so I need to ask if anyone has seen this site. A while back I was looking around and found an online thesaurus where you could type in a paragraph of words and it would give you different words for each one (you didn't have to type one then go back and type another like you have to do on thesaurus.com) does anyone know of any sites like the one that I'm trying to find?