OpenStudy: Online homework help for all levels of math...and it's free! You can help or be helped (you get "medals" for helping...think of it as a game!).
Cramster: Website that offers solutions to odd numbered (and some even) problems for free.
Kahn Academy: This is a free resource providing video clips of intruction in all sorts of disciplines! Definitely worth a look...
DPGraph: Free 3-D graphing program you can download. (Instructions for download and use)
Link to WinPlot: Free graphing program you can download
The Futures Channel: Videos on how math relates to various types of jobs and careers, from farming to designing roller-coasters.
Free-fall with Air Resistance: Amazing video of people "flying" with wing-suits.
The International Space Station: Shows how the Space Station has grown since its inception in 1998.
Imagining the 10th Dimension: Very cool explanation of higher dimensions.
Calculus Rhapsody: Calculus students having way too much karaoke fun with Bohemian Rhapsody!