Here are some great Lewis and Clark sites - some historical in nature,
   Some focused on present day information :

            -The Lewis and Clark Discovery Expedition - A  great site run by
               folks who engage in river-based reenactments, with replicas of 
                Lewis and Clark's boats as a centerpoint. 

            -Lewis and Clark Trail Heritage Foundation, Inc.  - Comprehensive
               historical site.

            -Sacagawea - Some Information on the Shoshone woman who
               helped guide the expedition.

            -The National Lewis & Clark Bicentennial Council - Celebrating the 
               200th anniversary of the Lewis and Clark expedition.  Loaded
                with great information.