Amazon Interactive - Geography, games, and more!
The Borderland's Encyclopedia (U of Texas, El Paso)
Expressions of Central America (Stanford Center for Latin American Studies and the School of Education's Learning, Design, and Technology Program) See "Student Interactivities" under Honduras and Nicaragua for some cool puzzles and activities.
Fact Monster (from Information Please)
The Global Schoolhouse
Little Explorers English/Spanish dictionary
The Mesoamerican Ballgame (Play, watch, and learn! This awesome site requires the latest Flash plug-in. Download provided.)
Spanish Tongue Twisters: Trabalenguas (Michael Reck)
Tropical America (Latin American History Game - OnRamp Arts)