33. A method for generating and using fault-tolerant speech recognition grammars, the method comprising: generating a master grammar set that contains textual representations of valid search query utterances; subdividing the master grammar set according to the first N characters of the textual representations of valid search query utterances to generate multiple speech recognition grammars, such that different speech recognition grammars correspond to different N-character sequences; storing said multiple speech recognition grammars in a data repository in association with the N-character sequences to which they correspond; and subsequently, via execution of software by a computerized system, interpreting a sequence of N character utterances of a user to generate a sequence of N characters; selecting from said data repository the speech recognition grammar corresponding to said sequence of N characters; and using the selected speech recognition grammar to interpret an utterance by the user of a search query; wherein N is less than the number of characters in the uttered search query, and wherein subdividing the master grammar set comprises treating a set of two or more similar sounding characters as the same character so that multiple N-character sequences map to the same speech recognition grammar.
39. The method of claim 33 , wherein: at least one character of said sequence of N character utterances is a member of said set of similar sounding characters; whereby misidentification of an uttered character in the set as a similar sounding character within the set does not cause the speech recognition grammar to be incorrectly selected.