1. A method implemented at least in part by a computing device, the method comprising: creating an index that maps each of multiple keywords to one or more phrases that each comprise at least one word; determining one or more statistically improbable phrases associated with a user, each of the one or more statistically improbable phrases comprising at least two contiguous words that occur in a corpus of text more than a threshold number of times; determining the words that compose the one or more statistically improbable phrases that are associated with the user; inputting, into the index as keywords, the determined words that compose the one or more statistically improbable phrases to determine phrases that are associated with the determined words that compose the one or more statistically improbable phrases; and outputting the determined phrases for suggestion to the user.