1. One or more processor-accessible tangible storage media storing processor-executable instructions for facilitating multimodal interaction, wherein the processor-executable instructions, when executed by a processor, perform a method comprising: receiving a spoken utterance including two or more terms, the two or more terms not being recognized as a permissible phrase that is in-grammar for a grammar-based speech application; recognizing one or more acceptable terms that are in-vocabulary from among the two or more terms of the spoken utterance; searching an index using the one or more acceptable terms as query terms; producing, from the searching of the index, at least one permissible phrase that is in-grammar and that includes the one or more acceptable terms; the index comprising a searchable data structure that represents multiple possible grammar paths that are ascertainable based on acceptable values for each term position of the grammar-based speech application; and presenting at least one permissible phrase to a user as at least one option that may be selected to conduct multimodal interaction with the device.
3. The one or more processor-accessible tangible storage media as recited in claim 1 , wherein the method comprises: traversing the multiple possible grammar paths of the grammar-based speech application based on the acceptable values for each term position of the grammar-based speech application; ascertaining, from the traversing of the multiple possible grammar paths, phrases that are permissible in accordance with the grammar-based speech application; and creating the index from the phrases that are permissible in accordance with the grammar-based speech application.