Explore Some Intercomprehension Websites
Learning to Comprehend Several Languages at the Same Time
I have previously posted about comparative books for learning several languages together, including EuROM5 which has an accompanying website. Here are some other intercomprehension websites for learning multiple languages at the same time. These projects focus on comprehending languages related to your native language or learning to understand closely related languages. Some of these projects offer explanations in English while others remain in the target languages only (usually Romance languages).
Union Latine – Some Romance language activities in Catalan, Spanish, French, Italian, Portuguese, and Romanian; six modules for learning all six languages (Romance Itineraries) and the game Limbo for learning Spanish and Portuguese
Euro-mania – Twenty lessons in six languages (Spanish, French, Italian, Portuguese, Occitan, and Romanian) on the topics of science, history, geography, technology and math

Sample page from first module of Euro-mania with integrated sound files
Micrela – Mutual intelligibility of closely related languages project with language game to test how well you can understand a European language related to your native language
European Awareness and Intercomprehension – Platform for comprehending 11 European languages (Bulgarian, Dutch, English, French, German, Greek, Italian, Portuguese, Spanish, Swedish or Turkish) based around traveling in Europe, with videos
Intermar – project designed to facilitate the reciprocal understanding and learning of languages through intercomprehension in a maritime context; materials in English (as the lingua franca at sea), Romance, Germanic, and Baltic languages