The Dickinson Electronic Archives is an online center dedicated to Dickinson's work. It features rare images of writing by Dickinson, her family and friends, as well as transcriptions of the faint, hard-to-read 19th century script. Unfortunately, you have to have a password to access some materials, but you can still find enough on here to sate your curiosity (or your research requirements).
The Poetry Foundation has a thorough, insightful biography of Dickinson, as well as links to her poems. It also has a detailed reading list and bibliography to point you in the right direction if you're doing an in-depth project.
The Academy is one of the best resources on the Web for poets and poetry. Dickinson's page offers a biography, as well as links to her poems and critical essays about her. We like poet Michael Ryan's essay on why Dickinson is his favorite poet.
Dickinson fan Erin has put together this swell website linking the best Dickinson-related sites and articles on the Web. Some of the links are out of date, but she has some fun finds. She also helpfully explains how to cite her page—don't plagiarize from her (or anyone)!
Dickinson spent almost her entire life in two homes in Amherst, Massachusetts: The Homestead, where she was born and raised, and the Evergreens, the house next door where her brother and sister-in-law lived. The two homes have now been turned into a museum dedicated to honoring Dickinson's life and works.
Associate professor Lilia Melani has put together a great Web component to her Brooklyn College course on Emily Dickinson. Her page has information on Dickinson's biography and poems, as well as some helpful instructions on how to read and analyze Dickinson's work.