GoBotany - New England plants
GoBotany is an online flora for the New England states sponsored by the New England Wildflower Society and NSF. Most of the plants in upstate NY are included in the database. There are photos, simple keys, full keys, ID help (presumably only for plants seen in New England), a glossary, maps and more.
The simple key is just that. The full key allows you to choose the characters for which you have data, and the program spits out possible matches. Very useful when you don't have key features (flowers!) but be careful to know the definitions of the features, and don't use more than you must.