There are many hotels in the Ithaca area, including one on the campus of the Cornell University:

The Statler Hotel at Cornell University - From $230/night

Best Western University Inn - $109/night + tax. For this rate, call the hotel @ (607)-272-6100 and mention that you are booking a room for the NA-ISMET meeting. This rate includes a continental breakfast and shuttle service to campus. To receive this special rate, you must book by September 8th, 2012.