http://echo.gmu.edu/

"ECHO (Exploring and Collecting History Online) is a portal to over 5,000 websites concerning the history of science, technology, and industry. This guide helps researchers find the exact information they need while also granting curious browsers a forum for exploration. 

ECHO is also a first step into the field of digital history: since 2001 it has been a laboratory for experimentation in this new field, and it fosters communication and dialog among historians, scientists, engineers, doctors, and technologists. In addition to facilitating access to digital resources on the history of science, technology, and industry, ECHO has promoted the creation of digital history with tools like Zotero and the construction of Digital Memory Bank technology (as in preserving the memories of Hurricane Katrina). We also help scholars and institutions with their own digital history projects through workshops and consultancies. 

The project is based at George Mason University's Center for History and New Media."