18. A user-interface system for selecting and presenting a collection of content items in which the presentation is ordered at least in part based on analyzing activity associated with content items having descriptive terms that describe the content items and promoting the presentation ranking of content items associated with descriptive terms that have an increased level of current activity, the system comprising: at least one non-transitory computer-readable media in at least one of a user device or a remote server system in communication with the user device, the computer-readable media comprising instructions that when executed cause a computer system to: provide access to a set of content items, each content item having at least one associated descriptive term to describe the content item; receive incremental input entered by users for incrementally identifying desired content items; present corresponding subsets of content items to the users in response to the incremental input entered by the users, receive actions from the users selecting content items from the corresponding subsets; analyze the selection actions received from the users to detect an increased level of current activity relative to an normal level of activity associated with the content items selected by the users; select and order a collection of content items based on promoting the ranking of content items associated with descriptive terms that are associated with content items that have the increased level of current activity relative to the normal activity level; and present the collection of content items to at least one user.
18. A user-interface system for selecting and presenting a collection of content items in which the presentation is ordered at least in part based on analyzing activity associated with content items having descriptive terms that describe the content items and promoting the presentation ranking of content items associated with descriptive terms that have an increased level of current activity, the system comprising: at least one non-transitory computer-readable media in at least one of a user device or a remote server system in communication with the user device, the computer-readable media comprising instructions that when executed cause a computer system to: provide access to a set of content items, each content item having at least one associated descriptive term to describe the content item; receive incremental input entered by users for incrementally identifying desired content items; present corresponding subsets of content items to the users in response to the incremental input entered by the users, receive actions from the users selecting content items from the corresponding subsets; analyze the selection actions received from the users to detect an increased level of current activity relative to an normal level of activity associated with the content items selected by the users; select and order a collection of content items based on promoting the ranking of content items associated with descriptive terms that are associated with content items that have the increased level of current activity relative to the normal activity level; and present the collection of content items to at least one user. 21. The system of claim 18 , wherein each of at least a plurality of the content items is associated with a corresponding popularity value indicating a relative measure of a likelihood that the corresponding content item is desired by the at least one user relative to the other content items of the plurality, and wherein the selecting and ordering the collection of content items includes promoting the order of content items having popularity values that are higher relative to popularity values associated with other content items.