This site from The New York State Museum features a compilation of regional and statewide geology/hydrology GIS datasets that are available in ArcInfo and ArcView formats. Datasets are separated into four categories: statewide - coverage for the whole state (may be comprised of several datasets), regional based data - coverage for a portion of the state, county based data - coverage for an entire county, and quad based data - coverage for an entire 7.5' quadrangle.