Hammond Hill is a fairly large state forest with a nice trail system.  It's popular with hikers and mountain bikers in the warmer months, and snowshoers and cross country skiers in the winter.  On the map below, the Finger Lakes Trail is shown in purple, while other trails are shown in blue.  You can get there by going north from Route 79 near Slaterville and Caroline, or by going south from Route 13 near Dryden, or by taking Ellis Hollow Road east from Ithaca, then turning left on Hurd, left on Irish Settlement, and right on Hammond Hill.  Note that Hammond Hill is also near Yellow Barn State Forest, Dryden Lake, and Robinson Hollow State Forest (lower right on this map, not marked).

Links for Hammond Hill State Forest:
http://www.dec.state.ny.us/website/dpae/cons/hammond.pdf
http://www.footprintpress.com/Snow_Trails/Hammond%20Hill%20SF.htm

Map courtesy of Tompkins County GIS