isokinetics magnetic pedal exerciser
This is not for "under your desk at work" but it does a fine job if you are sitting on a kitchen chair.  It does have a tendency to slide on any surface other than carpet so you might want to make a strap to go from the exerciser to the legs of your chair.<br />I have it for about a month and am pleased.  I pedal away while reading a magazine or book.  Great for when you don't want to go outside in the winter.
Rating: 4 stars