Has anyone seen any other pictures of this thing? I've only ever seen the official government one and the bottom looks photoshopped to me. Maybe to cover over the carnage or something? I'm not doubting its existence or severity, I'd just like to get another perspective to gage depth and whatnot.
In a four inch scope the planets are a good option. Jupiter and its satellites are always fun to look at and you should easily be able to see cloud bands on the planet's surface. If you're lucky you can likely even see the shadows of the moons cross the surface of the planet. Saturn is a must if at all possible. Unfortunately in the spring Orion may not be visible in the evenings so that rules out the Orion nebula (the only naked-eye nebula for the Northern hemisphere - not sure if there's anything down South). The Andromeda galaxy might be a good representative of a galactic object although there won't be much detail in a scope that size. I recommend checking out skyandtelescope.com and doing a search for local amateur astronomy groups in your area. You will likely find a local group that is willing to donate their time to present to your students and make their instruments available for an evening or more. They likely have 'scopes that far outstrip the four inch scope you already have access too which will give access to a whole range of diffuse and distant objects like galaxies and nebula.
NASA's Astronomy Picture of the Day
Come on people. Pay the $5. This is the exactly kind of behavior we keep asking for! They're releasing the source and not treating us like we're all thieves. Let's reward them for giving us the benefit of the doubt.
Besides, if you could afford to buy yourself an iPhone or iPod touch, you can likely afford it. (Especially considering what ATT charges for data packages.)
Solutions are obvious if one only has the optical power to observe them over the horizon. -- K.A. Arsdall