1. A computer-implemented user-interface system for incrementally finding and presenting one or more content items in response to keystrokes entered by a user on an input device having a known layout of overloaded keys selected from a set of key layouts, each overloaded key having a corresponding set of alphanumeric symbols, the system comprising: a database stored in a computer memory, the database containing content items and corresponding descriptive terms that characterize the content items; a computer memory comprising instructions for causing a computer system to: receive keystrokes from the user and build a string corresponding to incremental entries by the user, each item in the string having the set of alphanumeric symbols associated with a corresponding keystroke; map the string to the database to find the most likely content items corresponding to the incremental entries, the mapping being in accordance with a defined error model, the error model corresponding to the known layout of overloaded keys of the input device; wherein the error model associates the string with: (i) suggested corrections for typographic errors corresponding to incremental user entries, wherein suggested corrections are derived by replacing characters in the string resulting from one or more accidently pressed adjacent keys; (ii) suggested corrections for orthographic errors corresponding to incremental user entries, wherein suggested corrections are derived by replacing one or more characters in the string resulting from phonetic substitutions; and wherein the most likely content items are ordered and presented on a display device in accordance with defined ordering criteria; such that the user-interface system receives ambiguous entries from the user and presents the most likely matching content items.
7. The system of claim 1 , wherein the database contains pre-computed variants of the descriptive terms that characterize the content items and the mapping logic maps the incremental entries to the pre-computed variants.