Anti-Imperialism in the United States
http://www.boondocksnet.com/ail98-35.html
Primary and secondary material about the annexation of the Phillipines and the Anti-Imperialist League.

Hawaii: Independent & Sovereign
http://www.hawaii-nation.org/index.html
Information about the American annexation of Hawaii, and calls for its reversal.

Sentenaryo/Centennial: The Philippine Revolution and the Philippine-American War
http://www.boondocksnet.com/centennial/index.html
Essays, documents, and photographs (including some fascinating stereographic views). A very thorough site.