I eagerly await this forthcoming Exoplanet Visualization Tool called 'exoExplorer' being developed by the Planetary Biology Team. The software is set to be released in June 2008.
From the looks of it, the exoExplorer visual interface will depict the exoplanet's surface features and environmental appearance based on its known characteristics as inferred from the exoplanet data.
The interface will be highly interactive - almost like a game, and as such I foresee a kind of immersive 3D experience, and your avatar will be a spaceship or a rover.
Head over to their project page to find out more. June 2008 is just around the corner for its release. I'll keep you posted.