There was a piece in www.marthastewart.com program guide on August
4th. I think it was on her television show and you can probably find
it with a site-wide search. I didn't see the show but periodically
look through the site. I thought I'd also saved a recent ginger
article from the New York Times but I don't see the article now.....
Anyway, Martha's piece is one of her "good thing" columns and in it
she's got Madhur Jaffrey describing how to buy and store ginger.
In it she says that for more longterm storage, basically plant a knob
in potting soil and keep it a little moist but don't overwater it. It
should be kept in a sunny place. Just dig it up and break off a piece
when you want. Also, it appears that there are sprouts that can also
be used but the article didn't specify how.
I'm trying it now for the first time. Don't know how fast it grows or
whether I started off with a big enough piece though.